doc/usage/linux: Update desktop integration how-to (#1742)
doc/usage/linux: Update desktop integration how-to (#1742)

From now on, the Cozy Desktop AppImages won't include any code to
integrate the app with the user's desktop (see
https://www.electron.build/configuration/appimage).

For integrating the app with a linux desktop the user now needs to
install the previously optional `appimaged` daemon and move the
AppImage file in specific locations.

The documentation now reflects those changes and some changes to the
supported distributions: some old unsupported distributions were
removed from the list and the newest Fedora and Debian (thanks
@Picus13) were added.
cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop