Move pull request template into .github/

and add an `.md` extension, and make the ordered list into headings!

Author: meatballhat

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,7 @@
+## What is the problem that this PR is trying to fix?
+
+## What approach did you choose and why?
+
+## How can you test this?
+
+## What feedback would you like, if any?