A few options aren't documented in the manpages. This commit adds
documentation for them based on the --help output and relevant commit
messages. Some of it could probably use more elaboration.
If this is set for a remote we will never automatically look for
dependencies in it. This makes dependency search faster, as we
don't need to search in app-only remotes.
This new command relies on flatpak_dir_update_remote_configuration()
and allows updating the local configuration for the remotes based on
the extra metadata present in the OSTree repo's summary file.
This parameter can still be combined with --title and --default-branch,
which take precedence when combined with --update.
