[gspell] docs: shorten hacking file

[Sébastien Wilmet <swilmet src gnome org>]

commit 48547077e172b59e45af845295a4e859f51a9f07
Author: Sébastien Wilmet <sw swilmet be>
Date:   Wed May 26 03:50:12 2021 +0200

    docs: shorten hacking file
    
    Remove less useful or redundant infos.

 HACKING | 7 -------
 1 file changed, 7 deletions(-)
---
diff --git a/HACKING b/HACKING
index 69a8185..aa73c99 100644
--- a/HACKING
+++ b/HACKING
@@ -18,10 +18,3 @@ Notes
 
 gspell follows the same guidelines and code conventions as GtkSourceView (when
 GtkSourceView was still developed by Sébastien Wilmet).
-
-The gspell GitLab:
-
-    https://gitlab.gnome.org/GNOME/gspell
-
-See the text files in the docs/ directory (if you're looking to integrate
-gspell with *Flatpak*, it's there ;-) ).