Clarify where metadata are stored exactly in the `bare-user` case.
Make the first sentence of `bare-user` and `bare-user-only` paragraph
symetric to make it easier to jump to the right paragraph for readers
in a hury. Stree out that `bare-user-only` may loose metadata.
Signed-off-by: Stefan Agner <stefan.agner@toradex.com>