Validate PR template has been update in PR validator

[makubacki]

The Mu DevOps PR Formatting Validator workflow validates correct formatting of PR descriptions in Project Mu repos.

---

The PR formatter should be updated to check that these instructions have been followed:

1. Replace this text with an actual descrption:

   <_Include a description of the change and why this change was made._>

2. Remove this line of instructions so the PR description shows cleanly in release notes:

   "For details on how to complete to complete these options and their meaning refer to [CONTRIBUTING.md](https://github.com/microsoft/mu/blob/HEAD/CONTRIBUTING.md)."

3. For each checkbox in the PR description, place an "x" in between [ and ] if true. Example: [x].
   (you can also check items in the GitHub UI)

   • [] Impacts functionality?
     • Functionality - Does the change ultimately impact how firmware functions?
     • Examples: Add a new library, publish a new PPI, update an algorithm, ...
   • [] Impacts security?
     • Security - Does the change have a direct security impact on an application,
       flow, or firmware?
     • Examples: Crypto algorithm change, buffer overflow fix, parameter
       validation improvement, ...
   • [] Breaking change?
     • Breaking change - Will anyone consuming this change experience a break
       in build or boot behavior?
     • Examples: Add a new library class, move a module to a different repo, call
       a function in a new library class in a pre-existing module, ...
   • [] Includes tests?
     • Tests - Does the change include any explicit test code?
     • Examples: Unit tests, integration tests, robot tests, ...
   • [] Includes documentation?
     • Documentation - Does the change contain explicit documentation additions
       outside direct code modifications (and comments)?
     • Examples: Update readme file, add feature readme file, link to documentation
       on an a separate Web page, ...

4. Replace this text as instructed:

   <_Describe the test(s) that were run to verify the changes._>

5. Replace this text with as instructed:

   <_Describe how these changes should be integrated. Use N/A if nothing is required._>