Update CONTRIBUTING.md

Fixed the headers. They were rendering incorrectly on GitHub for some weird reason; I copied the strings and rewrote the ## characters at the beginning and now they render as they should.

Signed-off-by: Per Lundberg <per.lundberg@ecraft.com>

CONTRIBUTING.md

 # Contributing to the registry
-## Before reporting an issue...
+## Before reporting an issue...
 ### If your problem is with...
@@ -35,7 +35,7 @@ By following these simple rules you will get better and faster feedback on your
  - search the bugtracker for an already reported issue
-### If you found an issue that describes your problem:
+### If you found an issue that describes your problem:
  - please read other user comments first, and confirm this is the same issue: a given error condition might be indicative of different problems - you may also find a workaround in the comments
  - please refrain from adding "same thing here" or "+1" comments