Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -59,5 +59,5 @@ If you wish to start working on an accepted proposal, please reply to the thread
 ##### In Progress
 Once a developer has begun work on a proposal, either from the core Xamarin.Forms team or a community member, the proposal is marked as in progress with the implementors name and (possibly) a link to a development branch to follow along with progress.
 
-### Rejected
+#### Rejected
 Rejected proposals will not be implemented or merged into Xamarin.Forms. Once a proposal is rejected, the thread will be closed and the conversation is considered completed, pending considerable new information or changes..