Fix coredns.1 manpage (#2756)

Signed-off-by: Miek Gieben <miek@miek.nl>

coredns.1.md

-## Name
+## CoreDNS
 
 *coredns* - plugable DNS nameserver optimized for service discovery and flexibility.
 
 ## Synopsis
 
-*coredns* *[OPTION]*...
+*coredns* **[-conf FILE]** **[-dns.port PORT}** **[OPTION]**... 
 
 ## Description
 
 CoreDNS is a DNS server that chains plugins. Each plugin handles a DNS feature, like rewriting
 queries, kubernetes service discovery or just exporting metrics. There are many other plugins,
 each described on <https://coredns.io/plugins> and there respective manual pages. Plugins not
-bundled in CoreDNS are listed on <https://coredns.io/explugins>.
+bundled by default in CoreDNS are listed on <https://coredns.io/explugins>.
 
-When started with no options CoreDNS will looks for a file names `Corefile` in the current
+When started with no options CoreDNS will look for a file names `Corefile` in the current
 directory, if found it will parse its contents and start up accordingly. If no `Corefile` is found
 it will start with the *whoami* plugin (coredns-whoami(7)) and start listening on port 53 (unless
 overridden with `-dns.port`).