Document --keep-index's short form -k in both main synopsis and
the save synopsis in the Options section.
Signed-off-by: John Marshall <jm18@sanger.ac.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
OPTIONS
-------
-save [-p|--patch] [--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [<message>]::
+save [-p|--patch] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [<message>]::
Save your local modifications to a new 'stash', and run `git reset
--hard` to revert them. The <message> part is optional and gives