Add -M short flag for --amend

Author: Neved4

builtin/commit.c

@@ -1687,7 +1687,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
  STATUS_FORMAT_LONG),
 OPT_BOOL('z', "null", &s.null_termination,
  N_("terminate entries with NUL")),
-OPT_BOOL(0, "amend", &amend, N_("amend previous commit")),
+OPT_BOOL('M', "amend", &amend, N_("amend previous commit")),
 OPT_BOOL(0, "no-post-rewrite", &no_post_rewrite, N_("bypass post-rewrite hook")),
 { OPTION_STRING, 'u', "untracked-files", &untracked_files_arg, N_("mode"), N_("show untracked files, optional modes: all, normal, no. (Default: all)"), PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
 OPT_PATHSPEC_FROM_FILE(&pathspec_from_file),