The --verbose and --ostree-verbose options are global to all
subcommands, but --version can only be used with the main "flatpak"
command, so fix the man pages to reflect that.
- Fix typos in doc/flatpak-install and doc/flatpak-update.
- The commands ending in -app were deprecated in commit f7a1fdaa,
so update a few remaining references to them.
- flatpak-update is used for runtimes and applications, so fix its short
description.