Added changelog for 7.11

Signed-off-by: Jeroen van Baarsen <jeroenvanbaarsen@gmail.com>

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
+v 7.11.0 (unreleased)
+  -
+  -
+  -
+  -
+  -
+  -
+  -
+  -
+
 v 7.10.0 (unreleased)
   - Allow users to be invited by email to join a group or project.
   - Don't crash when project repository doesn't exist.