github: comment contrib repo change explanation in pull request template

[xrmx]

Description

So that the massive explanation is not rendered after PR has been opened. Comment also the description explanation while we are at it.

Type of change

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• [ ] Test A

Does This PR Require a Contrib Repo Change?

• [ ] Yes. - Link to PR:
• [ ] No.

Checklist:

• [ ] Followed the style guidelines of this project
• [ ] Changelogs have been updated
• [ ] Unit tests have been added
• [ ] Documentation has been updated

[xrmx]

I think would also be nice to put these as comment too. Wdyt?

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

done, thanks