modify the pr template: comment out the kind examples (#295)

Signed-off-by: gy95 <guoyao17@huawei.com>

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,15 +1,19 @@
 **What type of PR is this?**
-> Uncomment only one ` /kind <>` line, hit enter to put that in a new line, and remove leading whitespace from that line:
->
-> /kind api-change
-> /kind bug
-> /kind cleanup
-> /kind deprecation
-> /kind design
-> /kind documentation
-> /kind failing-test
-> /kind feature
-> /kind flake
+
+<!--
+Add one of the following kinds:
+
+/kind api-change
+/kind bug
+/kind cleanup
+/kind deprecation
+/kind design
+/kind documentation
+/kind failing-test
+/kind feature
+/kind flake
+
+-->
 
 **What this PR does / why we need it**: