Fix some typos in code comment

server/events.go

@@ -270,7 +270,7 @@ func newPubMsg(c *client, sub, rply string, si *ServerInfo, hdr map[string]strin
 	} else {
 		m = &pubMsg{}
 	}
-	// When getting something from a pool it is criticical that all fields are
+	// When getting something from a pool it is critical that all fields are
 	// initialized. Doing this way guarantees that if someone adds a field to
 	// the structure, the compiler will fail the build if this line is not updated.
 	(*m) = pubMsg{c, sub, rply, si, hdr, msg, oct, echo, last}