tsflags=nodocs meas that nothing that's marked as %doc gets installed.
This includes among other things files in /usr/share/help, which are
needed for displaying built-in documentation for GNOME apps.
This commit drops the tsflags=nodocs the we inherited from the container
base image as built-in yelp documentation is often exposed through the
UI in various flatpak apps and dropping the help files breaks it.
