This incompatible change fixes an inconsistency with other commands
where '-L' is short for '--load-path'.
* guix/scripts/refresh.scm (%options): Add --load-path option from
%STANDARD-BUILD-OPTIONS. Remove #\L shortcut for --list-updaters, and
remove --load-path option that lacked the #\L shortcut.
(show-help): Update accordingly.
* doc/guix.texi (Invoking guix refresh): Update accordingly.