[DOCS Day] Contribution Guidelines Update (#2863)

* feat: initial commit with new handbook material

- Adds guides related to creating PR's
- Enhances PR templates

* feat: harmonized docs

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,14 +1,48 @@
 <!--
-Thank you for submitting a pull request! Please note that by contributing to Coral, you agree to our Code of Conduct: http://code-of-conduct.voxmedia.com/
 
-Before submitting your PR, please verify that:
+Thank you for submitting a pull request! Please note that by contributing to
+Coral, you agree to our Code of Conduct: http://code-of-conduct.voxmedia.com/
+
+Before submitting your Pull Request (or PR), please verify that:
+
 * [ ] Your code is up-to-date with the base branch
 * [ ] You've successfully run `npm run test` locally
 
 Refer to CONTRIBUTING.MD for more details.
+
   https://github.com/coralproject/talk/blob/master/CONTRIBUTING.md
+
 -->
 
 ## What does this PR do?
 
+<!--
+
+In this section, you should be describing what other Github issues or tickets
+that this PR is designed to addressed.
+
+Any related Github issue should be linked by adding its URL to this section.
+
+-->
+
+## What changes to the GraphQL/Database Schema does this PR introduce?
+
+<!--
+
+In this section, you should describe any changes to be made to the GraphQL
+schema file (located https://github.com/coralproject/talk/blob/master/src/core/server/graph/schema/schema.graphql) or any
+database model (located as types in the https://github.com/coralproject/talk/blob/master/src/core/server/models directory).
+
+If no changes were added to the GraphQL/Database Schema as a part of this PR,
+simply write "None".
+
+-->
+
 ## How do I test this PR?
+
+<!--
+
+In this section, you should be describing any manual testing that can be used to
+verify features introduced or bugs fixed in this PR.
+
+ -->