Add GitHub pull request template (#235)

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,10 @@
+<!-- Thank you for helping AAD Pod Identity with a pull request! -->
+
+**Reason for Change**:
+<!-- What does this PR improve or fix in AAD Pod Identity? Why is it needed? -->
+
+
+**Issue Fixed**:
+<!-- If this PR fixes GitHub issue 1234, add "Fixes #1234" to the next line. -->
+
+**Notes for Reviewers**: