man/checkout: document missing options
man/checkout: document missing options

Document missing options in the ostree checkout man page.

Signed-off-by: Stefan Agner <8bf81831f67286fff829779134e88c94b37210a1@toradex.com>

GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree