feat: adding 'documentation' type to pyproject

[germa89]

Description

I want to have a Documentation section in the release page.

I believe this is an starting point, but because of this: https://github.com/ansys/actions/blob/d01c6d2b1098b42ea9657767171034607431bb67/doc-changelog/action.yml#L120-L125

I think there inner plumbing is still not in place.

Issue linked

N/A

Checklist

• [x] I have visited and read Develop PyMAPDL.
• [ ] I have tested my changes locally
• [ ] I have added necessary documentation or updated existing documentation.
• [ ] I have followed the PyMAPDL coding style guidelines.
• [ ] I have added appropriate unit tests that also ensure the minimal coverage criteria.
• [x] I have reviewed my changes before submitting this pull request.
• [ ] I have linked the issue or issues that are solved to the PR if any.
• [x] I have assigned this PR to myself.
• [ ] I have marked this PR as draft if it is not ready to be reviewed yet.
• [x] I have made sure that the title of my PR follows Commit naming conventions (e.g. feat: adding new MAPDL command)