Update readme.

### Dependencies

The shell snippets assume zsh (the `**/*.ext` idiom gets used a lot).

Need a `gcc` toolchain.  Need the `unzip` and `zoo` utilities.

Need a `gcc` toolchain.  Need the `unzip`, `unar` and `zoo` utilities.

### File conversions

I think these are mail archives.  Might need a script to turn those

into mbox files.

### .zoo and .zip files

### Unpacking archives.

Within the zip files there are sometimes other archive files.

These had to be extracted.

```

for f in **/*.zoo; do

  (cd ${f%\/*} && zoo -extract ${f##*\/} && git rm ${f##*\/});

  (cd ${f%\/*} && zoo -extract ${f##*\/} && rm ${f##*\/});

done

```

```

for f in **/*.zip; do

  (cd ${f%\/*} && unzip ${f##*\/} && git rm ${f##*\/});

  (cd ${f%\/*} && unzip ${f##*\/} && rm ${f##*\/});

done

```

For .lzh files:

```

for f in **/*.lzh; do

  (cd ${f%\/*} && unar ${f##*\/} && rm ${f##*\/});

done

```