[ticket/12714] Switching the description of radio buttons to align the correct description above the listbox

https://tracker.phpbb.com/browse/PHPBB3-12714
or we just put "all forums" in its own dd tag.
I think it makes more sense to have all first and then the option  for the forum list.

otherwise the positioning in the code is a bit weird:
-> checkbox some forums
-> checkbox all forums
-> selectbox for "some forums"