Updated the usage string of git reset

Make git reset usage string reflect the command's behaviour and contents of
the man page.

Signed-off-by: Jan Stępień <jstepien@users.sourceforge.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-reset.c

@@ -23,7 +23,8 @@
 
 static const char * const git_reset_usage[] = {
 	"git reset [--mixed | --soft | --hard | --merge] [-q] [<commit>]",
-	"git reset [--mixed] <commit> [--] <paths>...",
+	"git reset [-q] <commit> [--] <paths>...",
+	"git reset --patch [<commit>] [--] [<paths>...]",
 	NULL
 };