Fix subheading in README.md (#1145)

README.md

@@ -85,8 +85,7 @@ Note: the script will take a long time to run (on my laptop more than 7 hours).
 - `bugbug/labels.py` contains utility functions for handling labels;
 - `bugbug/bug_snapshot.py` contains a module to play back the history of a bug.
 
-
-## Using bugbug for non-Mozilla projects
+## Using bugbug for non-Mozilla projects
 
 Bugbug is focussing on Mozilla use-cases for Firefox and Bugzilla.
 However, we will be happy to accept pull requests adding support for other projects or bug trackers.