Create PULL_REQUEST_TEMPLATE.md

.github/PULL_REQUEST_TEMPLATE.md

+<!--
+PLEASE READ THIS MESSAGE.
+
+HOW TO WRITE A GOOD PULL REQUEST?
+
+- Make it small.
+- Do only one thing.
+- Avoid re-formatting.
+- Make sure the code builds and works.
+- Write useful descriptions and titles.
+- Address review comments in terms of additional commits.
+- Do not amend/squash existing ones unless the PR is trivial.
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+-->
+
+### What does this PR do?
+
+<!-- A brief description of each change being made with this pull request. -->
+
+### Closes Issue(s)
+
+<!-- List here all the issues closed by this pull request. Use keyword `closes` before each issue number -->
+
+### Motivation
+
+<!-- What inspired you to submit this pull request? -->
+
+### More
+
+<!-- Anything else we should know when reviewing? -->
+- [ ] Added/updated documentation