Update https://wiki.ubuntu.com/StableReleaseUpdates with new urls

[panlinux]

https://wiki.ubuntu.com/StableReleaseUpdates should be updated to point to this docs set as opposed to the old SRU docs location (even though there are redirects in place, it's still potentially confusing).

[rkratky]

Related (or rather, this issue should be a part of): #346.