Add golang reference badge

Signed-off-by: leonnicolas <[email protected]>

Author: leonnicolas

README.md

@@ -1,5 +1,7 @@
 # iptables-parser
 
+[![Documentation](https://godoc.org/github.com/kilo-io/iptables_parser?status.svg)](http://godoc.org/github.com/kilo-io/iptables_parser)
+
 Parse lines generated by `iptables-save`.
 This parser is inspired by [Ben Johnson's SQL Parser](https://github.com/benbjohnson/sql-parser).