haproxy: clarify handling of http and socket addresses

This behaviour was introduced along with socket support, but never got
documented properly.

plugins/inputs/haproxy/haproxy.go

@@ -94,12 +94,15 @@ var sampleConfig = `
   ## An array of address to gather stats about. Specify an ip on hostname
   ## with optional port. ie localhost, 10.10.3.33:1936, etc.
   ## Make sure you specify the complete path to the stats endpoint
-  ## ie 10.10.3.33:1936/haproxy?stats
+  ## including the protocol, ie http://10.10.3.33:1936/haproxy?stats
   #
   ## If no servers are specified, then default to 127.0.0.1:1936/haproxy?stats
   servers = ["http://myhaproxy.com:1936/haproxy?stats"]
-  ## Or you can also use local socket
-  ## servers = ["socket:/run/haproxy/admin.sock"]
+  ##
+  ## You can also use local socket with standard wildcard globbing.
+  ## Server address not starting with 'http' will be treated as a possible
+  ## socket, so both examples below are valid.
+  ## servers = ["socket:/run/haproxy/admin.sock", "/run/haproxy/*.sock"]
 `
 
 func (r *haproxy) SampleConfig() string {