provide documentation/information on uberspace commands

[pascoda]

as discussed with jonas: for some users, it might be interesting/helpful to know what the various uberspace commands do.

the information does not have to be visible at all times, could be realised with expanding text fields (~ ausklappbare infobox).

to reduce maintenance workload, uberspace command doc could be put in a repo to include as sub-repo in both manual and lab.