[chore/github]: Standardize GitHub PR description template

Replace legacy templates with unified pull_request_template.md
(description, type, approach, documentation).

Signed-off-by: Oleksandr Ivantsiv <oivantsiv@nvidia.com>

Author: oleksandrivantsiv

.github/copilot-instructions.md

@@ -75,6 +75,11 @@ make
 - **CLA**: Sign Linux Foundation EasyCLA
 - **State machine**: Document state transition changes
 - **Testing**: Add unit tests for new state transitions or link management logic
+- **PR description template**: Fill out all sections of the [PR template](.github/pull_request_template.md) when submitting a pull request:
+  - **Description of PR**: Summary of the change, motivation/context, reviewer entry point, and dependencies; reference issues with `fixes #xxxx` / `closes #xxxx`.
+  - **Type of change**: Mark the box(es) that apply — bug fix, new feature, refactor / cleanup, documentation update, test improvement.
+  - **Approach**: Motivation; how you did it; how you verified/tested it; any platform-specific notes.
+  - **Documentation**: Link to wiki / doc updates relevant to new features or test cases.
 
 ## Common Patterns
 

.github/pull_request_template.md

@@ -24,24 +24,22 @@ Fixes # (issue)
 
 - [ ] Bug fix
 - [ ] New feature
-- [ ] Doc/Design
-- [ ] Unit test
+- [ ] Refactor / cleanup
+- [ ] Documentation update
+- [ ] Test improvement
 
 ### Approach
 #### What is the motivation for this PR?
 
-##### Work item tracking
-- Microsoft ADO **(number only)**:
-
 #### How did you do it?
 
 #### How did you verify/test it?
 
 #### Any platform specific information?
 
-### Documentation 
+### Documentation
 <!--
 (If it's a new feature, new test case)
 Did you update documentation/Wiki relevant to your implementation?
 Link to the wiki page?
--->
+-->