[amtk] Update HACKING file

[Sébastien Wilmet <swilmet src gnome org>]

commit 352a65d17d0e10bd62050435ff941b0841ca3b3d
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Wed Apr 11 12:14:18 2018 +0200

    Update HACKING file

 HACKING |    5 +----
 1 files changed, 1 insertions(+), 4 deletions(-)
---
diff --git a/HACKING b/HACKING
index 8bbc55f..eea58c9 100644
--- a/HACKING
+++ b/HACKING
@@ -5,10 +5,7 @@ Amtk follows the same guidelines and code conventions as GtkSourceView:
 
     https://git.gnome.org/browse/gtksourceview/tree/HACKING
 
-Amtk is hosted on the GNOME GitLab instance, you can fork the repository
-and then do a merge request:
-
-    https://gitlab.gnome.org/GNOME/tepl
+To contribute, send a pull request by e-mail to the maintainer.
 
 Read the following wiki page to know the conventions for the commit messages: