[Release Docs] Add documentation and release notes for separate Competency Management and Taxonomy Editing screens

This issue adds user-facing release documentation for the workflow that separates the Competency Criteria screen from the Taxonomy Editing screen.

Documentation should explain how to access each screen from the vertical ellipses menu, when to select Apply Competencies, and when to select Edit Taxonomy. The documentation should make clear that competency criteria management and taxonomy editing are separate workflows.

Documentation should follow the same process used for the previous taxonomy editing work, with docs added to the Open edX documentation repository.

Release notes are not expected to be created as part of this ticket. Axim is experimenting with generating release notes separately, and the team may share those for review if needed.

Documentation Location:

Documentation should be added to the Open edX documentation repository:
https://github.com/openedx/docs.openedx.org

Outstanding/Needs Confirmation:

• Confirm the exact documentation page or section where the Competency Criteria and Taxonomy Editing workflow content should be added in the repository.