Add metaGOflow version metadata

[cymon]

When publishing the data products from a metaGOflow analysis as a RO-Crate, we'd like to be able to point to metadata for the version of metaGOflow that was used. We/I originally thought this itself might be a RO-Crate, but it is likely simpler to just archive a README.md for each tagged version release.

The README.md for each tagged version release would contain a link to the "software_versions.tsv" file and a list of the "database versions" extracted from here.

Currently we only have two version that we have used "1.0" and "develop branch - short head commit 3cf3a7d".

See also Issue #52