chore: update PR template (#12)

.github/pull-request-template.md

@@ -6,11 +6,21 @@
   Please read the contribution document: https://github.com/lacework/terraform-gcp-gar/blob/main/CONTRIBUTING.md
 --->
 
-***Issue***: Include link to the Jira/Github Issue
+## Summary
 
-***Description:***
-Provide a detailed description of the changes made by this pull request.
+<!--
+ Explain the **motivation** for making this change. What existing problem does the pull request solve?
+-->
+
+## How did you test this change?
 
-***Additional Info:***
-Include any other relevant information such as how to use the new functionality, screenshots, etc.
+<!--
+  How exactly did you verify that your PR solves the issue you wanted to solve?
+  Include any other relevant information such as how to use the new functionality, screenshots, etc.
+-->
 
+## Issue
+
+<!--
+  Include the link to a Jira/Github issue
+-->