Readbench - add docs for all output files

[pontushojer]

The current documentation only covers the generalstats.txt, singlenucerrorstats.txt, indelerrorstats.txt and readerrors.txt outputs.

There are many other files output by readbench not covered by the documentation

https://github.com/marbl/GQC/blob/514e0072d6bf89b3a9793220bfb7f1662b95669b/GQC/output.py#L63C1-L84C114