This basically translates the man-page from 'git-developerish' to plain
english, adding some almost-sample output from git-status so users can
recognize what will happen.
Also mention explicitly that --mixed updates the index, while --soft
doesn't. I understood the old text to mean "--mixed is exactly like
--soft, but verbose".
Signed-off-by: Andreas Ericsson <ae@op5.se> Signed-off-by: Junio C Hamano <junkio@cox.net>