Update PULL_REQUEST_TEMPLATE.md

Author: alexkrolick

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,9 +1,13 @@
+
+
+<!--
+
 Thank you for the PR! Contributors like you keep React awesome!
 
 Please see the Contribution Guide for guidelines:
 
 https://github.com/reactjs/reactjs.org/blob/master/CONTRIBUTING.md
 
-If your PR references an existing issue, please add the issue number below:
+If your PR references an existing issue, please add the issue number below
 
-#<Issue>
+-->