check docs and online help for warnings

[jodygarnett]

I noticed a change I did failed linux build (which uses maven to call mkdocs build --strict) but passed the docs workflow check (which only uses mike).

Updated the docs workflow to use mkdocs build --strict for docs and online help (so it can act as a quick check.

Checklist

• I have read the contribution guidelines
• Pull request provided for main branch, backports managed with label
• Good housekeeping of code, cleaning up comments, tests, and documentation
• Clean commit history broken into understandable chucks, avoiding big commits with hundreds of files, cautious of reformatting and whitespace changes
• Clean commit messages, longer verbose messages are encouraged
• API Changes are identified in commit messages
• Testing provided for features or enhancements using automatic tests
• User documentation provided for new features or enhancements in manual
• Build documentation provided for development instructions in README.md files
• Library management using pom.xml dependency management. Update build documentation with intended library use and library tutorials or documentation

[jodygarnett]

I am not sure on how it works for editing a github workflow? The "Documentation" workflow being edited here is not being run ...

I was able to run the workflow in my fork here: https://github.com/jodygarnett/core-geonetwork/actions/runs/8694855358

[jodygarnett]

This line will need to be modified when backported, and when a major release is made.

I found that if: does not need the conditional ${{ syntax.