GITHUB: Update PULL_REQUEST_TEMPLATE.md

Author: michal-shalev

Diff for: .github/PULL_REQUEST_TEMPLATE.md

@@ -1,10 +1,10 @@
-## What
-_Describe what this PR is doing._ 
+## What?
+_Describe what this PR is doing._
 
-## Why ?
-_Justification for the PR. If there is existing issue/bug please reference. For
-bug fixes why and what can be merged in a single item._
+## Why?
+_Justification for the PR. If there is an existing issue/bug, please reference it. For
+bug fixes, the 'Why?' and 'What?' can be merged into a single item._
 
-## How ?
-_It is optional but for complex PRs please provide information about the design,
+## How?
+_It is optional, but for complex PRs, please provide information about the design,
 architecture, approach, etc._