Add initial support to French (fr) translation of user-manual.
Note that it is not perfect, since the po4a tool loose some list item
indexes during PO to ASCIIDOC conversion (see asciidoc warning messages
during user manual generation).
Signed-off-by: Guillaume GARDET <guillaume.gardet@free.fr>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>