Update README in regard to ls(1)

I marked out -m, -s and -x, because they are either visual flags
for interactive mode, which are better solved with tools made for this
job, or superfluous in another sense.
For example, -s basically "steals" the job from du.
In general, some of these options might still be easy to implement.
The options -S and -f are important though, as they are sorting-options
with real use.

README

@@ -42,7 +42,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
 =*| ln              yes                          none
 =*| logger          yes                          none
 =*| logname         yes                          none
-=   ls              no                           (-C), -S, -f, -m, -s, -x
+=   ls              no                           (-C), -S, -f, (-m), (-s), (-x)
 =*| md5sum          non-posix                    none
 =*| mkdir           yes                          none
 =*| mkfifo          yes                          none