Fix descriptions of some options (tiny change)

src/tar.c

@@ -482,9 +482,9 @@ static struct argp_option options[] = {
   {"touch", 'm', 0, 0,
    N_("don't extract file modified time"), GRID+1 },
   {"same-owner", SAME_OWNER_OPTION, 0, 0,
-   N_("try extracting files with the same ownership"), GRID+1 },
+   N_("try extracting files with the same ownership as exists in the archive (default for superuser)"), GRID+1 },
   {"no-same-owner", NO_SAME_OWNER_OPTION, 0, 0,
-   N_("extract files as yourself"), GRID+1 },
+   N_("extract files as yourself (default for ordinary users)"), GRID+1 },
   {"numeric-owner", NUMERIC_OWNER_OPTION, 0, 0,
    N_("always use numbers for user/group names"), GRID+1 },
   {"preserve-permissions", 'p', 0, 0,