Add consul service tags to metric (#4155)

plugins/inputs/consul/README.md

@@ -33,6 +33,11 @@ report those stats already using StatsD protocol if needed.
   # tls_key = "/etc/telegraf/key.pem"
   ## Use TLS but skip chain & host verification
   # insecure_skip_verify = true
+
+  ## Consul checks' tag splitting
+  # When tags are formatted like "key:value" with ":" as a delimiter then
+  # they will be splitted and reported as proper key:value in Telegraf
+  # tag_delimiter = ":"
 ```
 
 ### Metrics: