Updated PR template.

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,16 +1,31 @@
-This template is not intended to be prescriptive, but to help us review pull requests it would be useful if you included as much of the following information as possible:
+## What does the pull request do?
 
-- What does the pull request do?
+Give a bit of background on the PR here, together with links to with related issues etc.
-- What is the current behavior?
-- What is the updated/expected behavior with this PR?
-- How was the solution implemented (if it's not obvious)?
 
-Checklist:
+## What is the current behavior?
+
+If the PR is a fix, describe the current incorrect behavior, otherwise delete this section.
+
+## What is the updated/expected behavior with this PR?
+
+Describe how to test the PR.
+
+## How was the solution implemented (if it's not obvious)?
+
+Include any information that might be of use to a reviewer here.
+
+## Checklist
 
 - [ ] Added unit tests (if possible)?
 - [ ] Added XML documentation to any related classes?
 - [ ] Consider submitting a PR to https://github.com/AvaloniaUI/Avaloniaui.net with user documentation
 
+## Breaking changes
+
+List any breaking changes here. When the PR is merged please add an entry to https://github.com/AvaloniaUI/Avalonia/wiki/Breaking-Changes
+
+## Fixed issues
+
 If the pull request fixes issue(s) list them like this:
 
 Fixes #123