* guix/scripts/home.scm (process-action): Handle operating-system declaration
and extract home environment for current user.
* doc/guix.texi (Guix Services)[Guix Home Service]: Document it.
Change-Id: I995f79c2549e6edc76322542d0422159e0b79996
Reviewed-by: Maxim Cournoyer <maxim.cournoyer@gmail>