Add PR template (#287)

Signed-off-by: xing-yang <[email protected]>

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,19 @@
+**What this PR does / why we need it**:
+
+**Which issue(s) this PR fixes**:
+<!--
+Usage: `Fixes #<issue number>`, or `Fixes (paste link of issue)`.
+-->
+Fixes #
+
+**Special notes for your reviewer**:
+
+**Does this PR introduce a user-facing change?**:
+<!--
+If no, just write "NONE" in the release-note block below.
+If yes, a release note is required:
+Enter your extended release note in the block below.
+-->
+```release-note
+
+```