doc: update link to Code of Conduct

PR-URL: #12552
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

CONTRIBUTING.md

@@ -4,7 +4,7 @@
 
 The Code of Conduct explains the *bare minimum* behavior
 expectations the Node Foundation requires of its contributors.
-[Please read it before participating.](./CODE_OF_CONDUCT.md)
+[Please read it before participating.](https://github.com/nodejs/TSC/blob/master/CODE_OF_CONDUCT.md)
 
 ## Issue Contributions