docs: adding warning about *mwrite. Update *vwrite warning to include *mwrite

[germa89]

Description

Warn about *MWRITE usage.

Issue linked

Referenced in #3289
Close #3290

Checklist

• 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.
• 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.
• I have assigned this PR to myself.
• I have marked this PR as draft if it is not ready to be reviewed yet.
• I have made sure that the title of my PR follows Commit naming conventions (e.g. feat: adding new MAPDL command)

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[clatapie]

It looks good to me!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.89%. Comparing base (d50f95c) to head (44cfd67).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3296      +/-   ##
==========================================
- Coverage   87.15%   85.89%   -1.26%     
==========================================
  Files          55       55              
  Lines        9768     9773       +5     
==========================================
- Hits         8513     8395     -118     
- Misses       1255     1378     +123