Update help manual to match file system support dialog (#342682)

The help manual was updated to reflect that the legend is now always
displayed on the File System Support dialog.

Bug #342682 - too much information in 'features' dialog
Add gnome-common to fedora dependencies in README

The gnome-common package is needed when building from the git
repository.  This package was missed in the list of dependencies for
the Fedora GNU/Linux distribution.
Update copyright year