Thanks for your work. There is indeed a great need for pages to be updated to account for everything that has happened with Plasma 5. Let me know if you have questions or want to discuss anything.
Please note, that the tags for the translation units (<!--T:nn-->) are created and maintained automatically by the translation system, they must not be added or changed by us. You can add new sections - the system will then add a new tag for it. You can modify the contents of an existing unit. You can move units around (moving the unit tag along with everything else) and you can delete units, also deleting the tag.
Thanks for introducing me. I really found the KDE documentation lacking; the last straw was when I saw a 3-page long Plasma Manual that was partially for KDE 4 and partially for KDE 5.2. Working on the UserBase Wiki will help with that, but is there a git for documentation?
There is a team working on documentation. You can get in touch with them on the IRC-channel #kde-docs (see also IRC Channels) or the mailinglist kde-doc-english (see also Mailing Lists). They produce the official docs that are distributed along with the Plasma desktop as well as individual applications.
UserBase was originally intended to be a place where users could share tips and tricks. At some point we had major effort to make UB reflect the (then) current state of things, and it was maintained for some time, but unfortunately there are not many active contributors left. I would very much like to get UB back on track. Any help is greatly appreciated.