Documentation markup improvements

[lsiepel]

Documentation is an essential part of openHAB, but keeping it consistent and error-free has been a recurring challenge. Currently, small markup errors are easily introduced, and historically we’ve had to create bulk PRs to fix these ad hoc.

To address this sustainably, I propose to:

1. Add a markup validation step to the build process.
   This will automatically catch common syntax and formatting issues during PR reviews.

2. Ensure all current documentation passes the validation
   As a prerequisite, I’ll create additional PR`s that correct existing issues across the bindings.

Once in place, the markup check will help maintain the quality of our documentation, reduce the need for future bulk fixes, and make contributions smoother for everyone.

I’ll use this issue to track the related PRs and progress. Feedback and suggestions are welcome!

• Add markdown action #19010
• Fix markdown bindings A-B #19012 (jsscripting needs another PR at other repo)
• Fix markdown bindings C-D #19013
• Fix markdown bindings E-F #19015 + [freebox] Remove binding #19000
• Fix markdown bindings G-H #19016
• Fix markdown bindings I-J #19017
• Fix markdown bindings K-L #19018
• Fix markdown bindings M-N #19025
• Fix markdown bindings O-P #19026
• Fix markdown bindings Q-S #19027
• Fix markdown bindings T-V #19028
• Fix markdown bindings W-Z #19032
• Fix markdown io / persistence / transform / voice #19034
• Fix markdown repo files #19033
• Improve meaningful links #19155
• Add markdown format paragraph openhab-docs#2542 (comment)

And some catchup PR's

• Markdown catchup #19885
• [jsscripting] Fix documentation markdown #20057
• Minor markdown issues #20058
• Fix vuepress vs markdown links #20060

The first PR that enables the Github action can be merged at any time. It will fail as long as the other PR's have not yet been merged.