Create separate FUSE related page

[TheAssassin]

@probonopd silently removed the notice on https://github.com/AppImage/AppImageKit/wiki/FUSE and restored some old, redundant contents. Not entirely sure why. But I guess it's because some information might be missing somewhere?

Anyway, we need better coverage of FUSE and related issues (also Docker etc.) in our docs.

[probonopd]

The information about FUSE on Docker was gone.

[TheAssassin]

I'm going to write some better information in the docs, and will replace the wiki page with a link to the docs then. I hate redundant information, and it's much easier to maintain the docs, which also have more features and some actual structure.