Update docs badge with new action name

[shimwell]

Description

the action name for the documentation has been changed so the badge needs a small update to the URL

Fixes issue

Checklist

• I'm making a PR from a feature branch on my fork into GEOUNED-org/GEOUNED/dev branch
• I have followed PEP8 style guide for Python or run a formatter such as black or ruff format on my code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works