update template

Author: slievrly

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,10 +1,10 @@
-Please make sure you have read and understood the contributing guidelines
+<!-- Please make sure you have read and understood the contributing guidelines -->
 
 ### Ⅰ. Describe what this PR did
 
 
 ### Ⅱ. Does this pull request fix one issue?
-If that, add "fixes #xxx" below in the next line, for example, fixes #99.
+<!-- If that, add "fixes #xxx" below in the next line, for example, fixes #97. -->
 
 
 ### Ⅲ. Why don't you add test cases (unit test/integration test)?