[gedit] Remove CONTRIBUTING.md, outdated and no longer needed

[Sébastien Wilmet <swilmet src gnome org>]

commit 318f29727b9b83542c189096859e67b15c9f84fc
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Aug 26 07:48:16 2019 +0200

    Remove CONTRIBUTING.md, outdated and no longer needed
    
    It explained to send patches on bugzilla! We are now on GitLab.
    
    And there is now a script dealing with pull requests on the GitHub
    mirror of GNOME repos, explaining that it is not the right place where
    to contribute.
    
    Note that there is of course the HACKING file that explains how to
    contribute.

 CONTRIBUTING.md | 8 --------
 1 file changed, 8 deletions(-)