[[Manual:User rights|User rights]] documentation
Right away I found two extensions that were using the rights field incorrectly, so I fixed them. I also found Extension:Ajax though, which has None entered into the rights and parameters field. Should that be removed to prevent the incorrect appearance of the extension adding user rights when it really doesn't?
Rights descriptions may not fit into the infobox well. "Perform captcha triggering actions without having to go through the captcha", which appears to be the longest extension-based right description on this wiki, spans two lines when I stick into the existing rights field. If there are several rights, or the descriptions are particularly long, that may get unwieldy. Also, getting the rights descriptions from messages is not something that will work in a lot of cases, because only a small amount of the extensions listed here are actually installed on MediaWiki.org. Perhaps it's best to just discuss the added rights in the extension documentation, as people are already being encouraged to do.
To avoid at least a part of the duplicated work, we could create a template which creates a table with names, description and notes, where the description is taken directly from system messages if you say the template to do so (when the extension is installed here). What do you think?