Changed 2 public links from http to https

CONTRIBUTING.md

@@ -47,9 +47,9 @@ PR is acceptable as an alternative.
 ## The Google Test and Google Mock Communities
 
 The Google Test community exists primarily through the
-[discussion group](http://groups.google.com/group/googletestframework) and the
+[discussion group](https://groups.google.com/group/googletestframework) and the
 GitHub repository. Likewise, the Google Mock community exists primarily through
-their own [discussion group](http://groups.google.com/group/googlemock). You are
+their own [discussion group](https://groups.google.com/group/googlemock). You are
 definitely encouraged to contribute to the discussion and you can also help us
 to keep the effectiveness of the group high by following and promoting the
 guidelines listed here.