Added a PR template (#1250)

.github/pull_request_template.md

@@ -0,0 +1,16 @@
+<!--  Thanks for sending a pull request!  Here are some tips for you:
+If this is your first time, please read our contributor guidelines: https://github.com/googleforgames/open-match/blob/master/CONTRIBUTING.md and developer guide https://github.com/googleforgames/open-match/blob/master/docs/development.md
+-->
+
+**What this PR does / Why we need it**:
+
+**Which issue(s) this PR fixes**:
+<!--
+*Automatically closes linked issue when PR is merged.
+Usage: `Closes #<issue number>`, or `Closes (paste link of issue)`.
+-->
+Closes #
+
+**Special notes for your reviewer**:
+
+