Page about the Super key

Hi all,

We received the ubuntu bug <https://launchpad.net/bugs/1779547> about 
this page:

https://help.gnome.org/users/gnome-help/stable/keyboard-key-super.html

The bug reporter claims that 5 of 5 items are incorrect and/or 
insufficient, and from an Ubuntu POV I fear he is right.

However, I suspect that there may be Ubuntu specific stuff which 
complicates it a bit. Therefore it would be great if someone could help 
to sort it, so we can decide a proper wording of the page upstream. Then 
I'll be happy to submit a pull request.

Thanks!

-- 
Gunnar Hjalmarsson
https://launchpad.net/~gunnarhj