update PR template

Author: vas3a

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,7 +1,12 @@
-Related JIRA Ticket:
-https://topcoder.atlassian.net/browse/<!-- JIRA TICKET ID -->
+<!--
+  NOTE: you can leave these comments as they are,
+  no need to delete them as they won't appear in the final PR description
+-->
+<!-- Please make sure to link the JIRA ticket related to this PR, if any -->
+## Related JIRA Ticket:
+https://topcoder.atlassian.net/browse/
 
-# What's in this PR?
-<!-- Please add a brief description of what this PR accomplishes -->
 
-<!-- SEE [Pull Requests](../README.md#pull-requests) for more details about opening a PR -->
+<!-- Please add a brief description of what this PR accomplishes -->
+<!-- SEE [Pull Requests](../README.md#pull-requests) for more details about opening a PR -->
+# What's in this PR?