Add PR template landing page (#3625)

* Add PR template landing page

* Fix emojis and line spacing

Author: markerikson

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,9 @@
+Thanks for the PR!
+
+To better assist you, please select the type of PR you want to create.
+
+Click the "Preview" tab above, and click on the link for the PR type:
+
+- [:bug: Bug fix or new feature](?template=bugfix.md)  
+- [:memo: Documentation Fix](?template=documentation-edit.md)  
+- [:book: New/Updated Documentation Content](?template=documentation-new.md)