Fix response_rcode_count_total metric (#3029)

plugin/forward/README.md

@@ -98,7 +98,7 @@ If monitoring is enabled (via the *prometheus* directive) then the following met
 
 * `coredns_forward_request_duration_seconds{to}` - duration per upstream interaction.
 * `coredns_forward_request_count_total{to}` - query count per upstream.
-* `coredns_forward_response_rcode_total{to, rcode}` - count of RCODEs per upstream.
+* `coredns_forward_response_rcode_count_total{to, rcode}` - count of RCODEs per upstream.
 * `coredns_forward_healthcheck_failure_count_total{to}` - number of failed health checks per upstream.
 * `coredns_forward_healthcheck_broken_count_total{}` - counter of when all upstreams are unhealthy,
   and we are randomly (this always uses the `random` policy) spraying to an upstream.

plugin/grpc/README.md

@@ -64,7 +64,7 @@ If monitoring is enabled (via the *prometheus* directive) then the following met
 
 * `coredns_grpc_request_duration_seconds{to}` - duration per upstream interaction.
 * `coredns_grpc_request_count_total{to}` - query count per upstream.
-* `coredns_grpc_response_rcode_total{to, rcode}` - count of RCODEs per upstream.
+* `coredns_grpc_response_rcode_count_total{to, rcode}` - count of RCODEs per upstream.
   and we are randomly (this always uses the `random` policy) spraying to an upstream.
 
 ## Examples