add link

README.md

@@ -28,7 +28,7 @@ Parse a IP address string to a object (with null prototype).
 For IPv4 returns `{number, version}`.
 For IPv6 returns `{number, version, [ipv4mapped], [scopeid]}`.
 
-There is only rudimentary validation that the passed string is actually an IP address. You are encouraged to validate yourself using modules like `ip-regex`.
+There is only rudimentary validation that the passed string is actually an IP address. You are encouraged to validate yourself using modules like [`ip-regex`](https://github.com/sindresorhus/ip-regex).
 
 ### stringifyIp({number, version, [ipv4mapped], [scopeid]}, [opts])