Documentation/stash: remove mention of git reset --hard

Don't mention git reset --hard in the documentation for git stash save.
It's an implementation detail that doesn't matter to the end user and
thus shouldn't be exposed to them.  In addition it's not quite true for
git stash -p, and will not be true when a filename argument to limit the
stash to a few files is introduced.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-stash.txt

@@ -47,8 +47,9 @@ OPTIONS
 
 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
+	Save your local modifications to a new 'stash' and roll them
+	back to HEAD (in the working tree and in the index).
+	The <message> part is optional and gives
 	the description along with the stashed state.  For quickly making
 	a snapshot, you can omit _both_ "save" and <message>, but giving
 	only <message> does not trigger this action to prevent a misspelled