docs: enrich PR request template (#120)

Author: hayk99

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,3 +1,23 @@
 <!--
-check contribution guidelines at https://github.com/sysdiglabs/terraform-aws-secure-for-cloud/blob/master/CONTRIBUTE.md#contribution-checklist
+Thank you for your contribution!
+
+## General recommendations
+Check contribution guidelines at https://github.com/sysdiglabs/terraform-aws-secure-for-cloud/blob/master/CONTRIBUTE.md#contribution-checklist
+
+For a cleaner PR make sure you follow these recommendations:
+- Review modified files and delete small changes that were not intended and maybe slip the commit.
+- Use Pull Request Drafts for visibility on Work-In-Progress branches and use them on daily mob/pairing for team review
+- Unless an external revision is desired, in order to validate or gather some feedback, you are free to merge as long as **validation checks are green-lighted**
+
+## Checklist
+
+- [ ] If `test/fixtures/*/main.tf` files are modified. I have updated: 
+    - [ ] the snippets in the README.md file under root folder.
+    - [ ] the snippets in the README.md file for the corresponding example. 
+- [ ] If `examples` folder are modified. I have updated:
+    - [ ] README.md file with pertinent changes.
+    - [ ] `test/fixtures/*/main.tf` in case the snippet needs modifications.
+- [ ] If any architectural change has been made, I have updated the diagrams. 
+    
 -->
+