SubmittingPatches: welcome the new maintainer of git-gui part

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/SubmittingPatches

@@ -531,9 +531,9 @@ patch, and "cc:" them when sending such a final version for inclusion.
 Some parts of the system have dedicated maintainers with their own
 repositories.
 
-- `git-gui/` comes from git-gui project, maintained by Pratyush Yadav:
+- `git-gui/` comes from git-gui project, maintained by Johannes Sixt:
 
-	https://github.com/prati0100/git-gui.git
+        https://github.com/j6t/git-gui
 
 - `gitk-git/` comes from Paul Mackerras's gitk project:
 

Documentation/git-gui.txt

@@ -114,7 +114,7 @@ of end users.
 
 The official repository of the 'git gui' project can be found at:
 
-  https://github.com/prati0100/git-gui.git/
+  https://github.com/j6t/git-gui
 
 GIT
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