I think the protocol number is what you are after, which shows on your second link, so that is essentially the latest server version supported by Oxide. Oxide is usually updated to the latest server version within hours, so you can usually tell the latest server version from that page, unless a server update was just posted. You can get the current version of your server with the "version" command.

Steam is the source of truth for latest server versions since that's where they are downloaded from.
https://steamdb.info/app/258550/history/