Merge "custom.css" and "documentation.css" in html/documentation/css #4842
Description
Historically, "documentation.css" was for the Allsky documentation pages and "custom.css" was for the WebUI.
Over time, however, the documentation started including setting names and section names from the WebUI, and in order to make them look identical to what users saw in the WebUI, some classes from custom.css were added to documentation.css. I forget why, but it didn't work to simply include both files - I think there were conflicts. And over time the WebUI started including items in the documentation, so "custom.css" started getting entries from "documentation.css".
What a mess it's become.
The two files should be merged, ideally with a new name, and that new file should be included in both the WebUI and documentation pages.
Further, we should weed out any entries no longer used.