[X2Go-User] Added wiki page doc:de-compat "Desktop Environment Compatibility"

http://wiki.x2go.org/doku.php/doc:de-compat

Contributions are welcome.

More info per distro and release of distro is needed. For example, which exact packages to install for GNOME3.

Also, references/links should be inserted throughout the wiki. I've added a few.

Also,

I tried to add a link to it on the "X2Go Documentation" box on the home page, but when I did so, the Documentation box became taller than the "Get Support" box, which in turn looks like crap. When I tried to add a single newline to the "Get Support" box according to the documentation here: https://www.dokuwiki.org/wiki:syntax#basic_text_formatting I instead added 2 new lines, so the "Get Support" box became taller than the "X2Go Documentation" box.

-Mike#2