I need to upgrade a 2.5.1 MU site to the latest WP Network version. But the only documentation I can find is obsolete (http://codex.wordpress.org/Upgrading_WPMU). It has a dead link for downloading software and seems to be about upgrading to an older MU version.
Is there a document for upgrading from the old version to the modern Network version so multiple blogs will be retained?
Or, if I install the latest Network version, is there documentation for moving the individual MU blogs into the new install?