[Tails-dev] Recommend add "check for Tails upgrade" in Tails…

I think it'd be good to add, under the "Tails" menu, an option
"Check for Tails Upgrade". This would run
"tails-upgrade-frontend-wrapper" and report "no upgrade available"
if none is available.

This would elminate the need to pull up the terminal in some cases
and implements part of this:
https://tails.net/upgrade/index.en.html