Document Migration from ftw

[dextermallo]

Hi go-ftw Team,

I am working on updating some documentation, and I found that some of the docs are missing in the go-ftw. (e.g., the format of the YAML test file)

And I found it in the ftw repo: https://github.com/coreruleset/ftw/tree/main/docs

Should we migrate the documentation to go-ftw?