Added hyperlink to dgrijalva#216

Author: odino

README.md

@@ -7,7 +7,7 @@ A [go](http://www.golang.org) (or 'golang' for search engine friendliness) imple
 
 **NEW VERSION COMING:** There have been a lot of improvements suggested since the version 3.0.0 released in 2016. I'm working now on cutting two different releases: 3.2.0 will contain any non-breaking changes or enhancements. 4.0.0 will follow shortly which will include breaking changes. See the 4.0.0 milestone to get an idea of what's coming. If you have other ideas, or would like to participate in 4.0.0, now's the time. If you depend on this library and don't want to be interrupted, I recommend you use your dependency mangement tool to pin to version 3. 
 
-**SECURITY NOTICE:** Some older versions of Go have a security issue in the cryotp/elliptic. Recommendation is to upgrade to at least 1.8.3. See issue #216 for more detail.
+**SECURITY NOTICE:** Some older versions of Go have a security issue in the cryotp/elliptic. Recommendation is to upgrade to at least 1.8.3. See issue [#216](https://github.com/dgrijalva/jwt-go/issues/216) for more detail.
 
 **SECURITY NOTICE:** It's important that you [validate the `alg` presented is what you expect](https://auth0.com/blog/critical-vulnerabilities-in-json-web-token-libraries/). This library attempts to make it easy to do the right thing by requiring key types match the expected alg, but you should take the extra step to verify it in your usage.  See the examples provided.