Add more stuff to changelog

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

CHANGELOG

@@ -20,6 +20,12 @@ v 7.4.0
   - Add select field type for services options (Sullivan Senechal)
   - Add cross-project references to the Markdown parser (Vinnie Okada)
   - Add task lists to issue and merge request descriptions (Vinnie Okada)
+  - Snippets can be public, internal or private
+  - Improve danger zone: ask project path to confirm data-loss action
+  - Raise exception on forgery
+  - Show build coverage in Merge Requests (requires GitLab CI v5.1)
+  - New milestone and label links on issue edit form
+  - Improved repository graphs
 
 v 7.3.2
   - Fix creating new file via web editor