Add PR template

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,14 @@
+**What this PR does / why we need it**:
+
+**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
+Fixes #
+
+**Special notes for your reviewer**:
+
+**Output/Demonstration
+<!--  Please feel free to add the demonstrations/changes the PR carries in this section.
+-->
+
+```release-note
+
+```