doc: regen man-pages (#3725)

Mechanical change: make -f Makefile.doc
Signed-off-by: Miek Gieben <miek@miek.nl>

man/coredns-cache.7

 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-CACHE" 7 "January 2020" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-CACHE" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -100,7 +100,7 @@ If monitoring is enabled (via the \fIprometheus\fP plugin) then the following me
 .IP \(bu 4
 \fB\fCcoredns_cache_misses_total{server}\fR - Counter of cache misses.
 .IP \(bu 4
-\fB\fCcoredns_cache_drops_total{server}\fR - Counter of dropped messages.
+\fB\fCcoredns_cache_drops_total{server}\fR - Counter of responses excluded from the cache due to request/response question name mismatch.
 .IP \(bu 4
 \fB\fCcoredns_cache_served_stale_total{server}\fR - Counter of requests served from stale cache entries.
 

man/coredns-cancel.7

 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-CANCEL" 7 "December 2019" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-CANCEL" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -19,6 +19,7 @@ A plugin interested in the cancellation status should call \fB\fCplugin.Done()\f
 context was canceled due to a timeout the plugin should not write anything back to the client and
 return a value indicating CoreDNS should not either; a zero return value should suffice for that.
 
+.SH "SYNTAX"
 .PP
 .RS
 

man/coredns-dnstap.7

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-.TH "COREDNS-DNSTAP" 7 "December 2019" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-DNSTAP" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -7,8 +7,8 @@
 
 .SH "DESCRIPTION"
 .PP
-dnstap is a flexible, structured binary log format for DNS software; see http://dnstap.info
-\[la]http://dnstap.info\[ra]. With this
+dnstap is a flexible, structured binary log format for DNS software; see https://dnstap.info
+\[la]https://dnstap.info\[ra]. With this
 plugin you make CoreDNS output dnstap logging.
 
 .PP
@@ -141,5 +141,5 @@ func (h Dnstap) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 .SH "SEE ALSO"
 .PP
 dnstap.info
-\[la]http://dnstap.info\[ra].
+\[la]https://dnstap.info\[ra].
 

man/coredns-forward.7

 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-FORWARD" 7 "January 2020" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-FORWARD" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -11,12 +11,14 @@ The \fIforward\fP plugin re-uses already opened sockets to the upstreams. It sup
 DNS-over-TLS and uses in band health checking.
 
 .PP
-When it detects an error a health check is performed. This checks runs in a loop, every \fI0.5s\fP, for
-as long as the upstream reports unhealthy. Once healthy we stop health checking (until the next
-error). The health checks use a recursive DNS query (\fB\fC. IN NS\fR) to get upstream health. Any response
-that is not a network error (REFUSED, NOTIMPL, SERVFAIL, etc) is taken as a healthy upstream. The
-health check uses the same protocol as specified in \fBTO\fP. If \fB\fCmax_fails\fR is set to 0, no checking
-is performed and upstreams will always be considered healthy.
+When it detects an error a health check is performed. This checks runs in a loop, starting with
+a \fI0.5s\fP interval and exponentially backing off with randomized intervals up to \fI15s\fP for as long
+as the upstream reports unhealthy. The exponential backoff will reset to \fI0.5s\fP after 2 minutes.
+Once healthy we stop health checking (until the next error). The health checks use a recursive
+DNS query (\fB\fC. IN NS\fR) to get upstream health. Any response that is not a network error (REFUSED,
+NOTIMPL, SERVFAIL, etc) is taken as a healthy upstream. The health check uses the same protocol as
+specified in \fBTO\fP. If \fB\fCmax_fails\fR is set to 0, no checking is performed and upstreams will always
+be considered healthy.
 
 .PP
 When \fIall\fP upstreams are down it assumes health checking as a mechanism has failed and will try to
@@ -66,7 +68,8 @@ forward FROM TO... {
     tls CERT KEY CA
     tls\_servername NAME
     policy random|round\_robin|sequential
-    health\_check DURATION
+    health\_check DURATION [no\_rec]
+    max\_concurrent MAX
 }
 
 .fi
@@ -124,7 +127,22 @@ but they have to use the same \fB\fCtls_servername\fR. E.g. mixing 9.9.9.9 (Quad
 
 .RE
 .IP \(bu 4
-\fB\fChealth_check\fR, use a different \fBDURATION\fP for health checking, the default duration is 0.5s.
+\fB\fChealth_check\fR configure the behaviour of health checking of the upstream servers
+
+.RS
+.IP \(en 4
+\fB\fC<duration>\fR - use a different duration for health checking, the default duration is 0.5s.
+.IP \(en 4
+\fB\fCno_rec\fR - optional argument that sets the RecursionDesired-flag of the dns-query used in health checking to \fB\fCfalse\fR.
+The flag is default \fB\fCtrue\fR.
+
+.RE
+.IP \(bu 4
+\fB\fCmax_concurrent\fR \fBMAX\fP will limit the number of concurrent queries to \fBMAX\fP.  Any new query that would
+raise the number of concurrent queries above the \fBMAX\fP will result in a SERVFAIL response. This
+response does not count as a health failure. When choosing a value for \fBMAX\fP, pick a number
+at least greater than the expected \fIupstream query rate\fP * \fIlatency\fP of the upstream servers.
+As an upper bound for \fBMAX\fP, consider that each concurrent query will use about 2kb of memory.
 
 
 .PP
@@ -155,12 +173,13 @@ If monitoring is enabled (via the \fIprometheus\fP plugin) then the following me
 .IP \(bu 4
 \fB\fCcoredns_forward_healthcheck_broken_count_total{}\fR - counter of when all upstreams are unhealthy,
 and we are randomly (this always uses the \fB\fCrandom\fR policy) spraying to an upstream.
-
-
-.PP
+.IP \(bu 4
+\fB\fCmax_concurrent_reject_count_total{}\fR - counter of the number of queries rejected because the
+number of concurrent queries were at maximum.
 Where \fB\fCto\fR is one of the upstream servers (\fBTO\fP from the config), \fB\fCrcode\fR is the returned RCODE
 from the upstream.
 
+
 .SH "EXAMPLES"
 .PP
 Proxy all requests within \fB\fCexample.org.\fR to a nameserver running on a different port:

man/coredns-k8s_external.7

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-.TH "COREDNS-K8S_EXTERNAL" 7 "December 2019" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-K8S_EXTERNAL" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -82,6 +82,7 @@ k8s\_external [ZONE...] {
 \fB\fCttl\fR allows you to set a custom \fBTTL\fP for responses. The default is 5 (seconds).
 
 
+.SH "EXAMPLES"
 .PP
 Enable names under \fB\fCexample.org\fR to be resolved to in-cluster DNS addresses.
 

man/coredns-kubernetes.7

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-.TH "COREDNS-KUBERNETES" 7 "January 2020" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-KUBERNETES" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -79,7 +79,7 @@ If this option is omitted all namespaces are exposed
 \fB\fCnamespace_labels\fR \fBEXPRESSION\fP only expose the records for Kubernetes namespaces that match this label selector.
 The label selector syntax is described in the
 Kubernetes User Guide - Labels
-\[la]http://kubernetes.io/docs/user-guide/labels/\[ra]. An example that
+\[la]https://kubernetes.io/docs/user-guide/labels/\[ra]. An example that
 only exposes namespaces labeled as "istio-injection=enabled", would use:
 \fB\fClabels istio-injection=enabled\fR.
 .IP \(bu 4

man/coredns-metrics.7

 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-METRICS" 7 "December 2019" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-METRICS" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -19,7 +19,7 @@ The following metrics are exported:
 .IP \(bu 4
 \fB\fCcoredns_dns_request_count_total{server, zone, proto, family}\fR - total query count.
 .IP \(bu 4
-\fB\fCcoredns_dns_request_duration_seconds{server, zone}\fR - duration to process each query.
+\fB\fCcoredns_dns_request_duration_seconds{server, zone, type}\fR - duration to process each query.
 .IP \(bu 4
 \fB\fCcoredns_dns_request_size_bytes{server, zone, proto}\fR - size of the request in bytes.
 .IP \(bu 4

man/coredns-rewrite.7

 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-REWRITE" 7 "January 2020" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-REWRITE" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -61,6 +61,7 @@ will behave as follows:
 \fB\fCstop\fR will consider the current rule the last rule and will not continue.  The default behaviour is \fB\fCstop\fR
 
 
+.SH "EXAMPLES"
 .SS "NAME FIELD REWRITES"
 .PP
 The \fB\fCrewrite\fR plugin offers the ability to match the name in the question section of

man/coredns-secondary.7

 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-SECONDARY" 7 "January 2020" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-SECONDARY" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -11,6 +11,7 @@ With \fIsecondary\fP you can transfer (via AXFR) a zone from another server. The
 \fInot committed\fP to disk (a violation of the RFC). This means restarting CoreDNS will cause it to
 retrieve all secondary zones.
 
+.SH "SYNTAX"
 .PP
 .RS
 

man/coredns-transfer.7

 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-TRANSFER" 7 "January 2020" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-TRANSFER" 7 "March 2020" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -39,3 +39,7 @@ block that serves the same zone, and implements \fB\fCtransfer.Transferer\fR.
 transfers to all hosts.
 
 
+.SH "EXAMPLES"
+.PP
+TODO
+