chore: improve pull request template to include kind lines in comment…

…s instead of quote (#1538)

Signed-off-by: Cheng Fang <cfang@redhat.com>

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,14 +1,15 @@
 **What type of PR is this?**
-> Uncomment only one ` /kind` line, and delete the rest.
-> For example, `> /kind bug` would simply become: `/kind bug`
-
-> /kind bug
-> /kind chore
-> /kind cleanup
-> /kind failing-test
-> /kind enhancement
-> /kind documentation
-> /kind code-refactoring
+
+[//]: # (Uncomment only one <!-- /kind ... --> line, and delete the rest.)
+[//]: # (For example, <!-- /kind bug --> would simply become: /kind bug  )
+
+<!-- /kind bug -->
+<!-- /kind chore -->
+<!-- /kind cleanup -->
+<!-- /kind failing-test -->
+<!-- /kind enhancement -->
+<!-- /kind documentation -->
+<!-- /kind code-refactoring -->
 
 
 **What does this PR do / why we need it**: