I couldn't find any good explanation about the About.xml, so I created a Wiki about it & put in what I know, the article is in a desperate need for further refining & development, so any help & information you can provide is very helpfull.
https://rimworldwiki.com/wiki/About.xml (https://rimworldwiki.com/wiki/About.xml)
Thank you!
The ModUpdating.txt file in the RimWorld folder has a LOT of the information you were probably looking for!