Call for help - Development documentation

[Confectrician]

Hey @openhab/core-maintainers and @openhab/add-ons-maintainers i need your help.

As proofed by https://community.openhab.org/t/getting-started-with-development-openhab-3-why-cant-i-access-paperui/114296/6 we still have leftover paper ui references in the development documentation. I have fixed this one and several others in openhab/openhab-docs#1457 already.
But while creating the PR i noticed some other probably outdated parts.
(Like references to OH1 addon development.)

I am not capable of reviewing and validating the development documentation completely on my own.
I can do the obvious changes and maybe some changes above the average user horizon, but not logical or content releated/breaking changes.
So your help here is appreciated/needed.

We already had several improving pull requests during the last year but i doubt that we got all old stuff out there yet.
We have also improvements that may be available in our 2.5.x branch but not yet in main openHAB 3 docs. I know of at least one contribution that could be cherrypicked if still valid.

Please help me out here and check, report, contribute updates to the development area.
If there are contents in 2.5.x available that should be moved to main docs branch let me know and i will cherry pick them into the latest docs.

Thanks in advance and stay safe everybody!