Check if the language of the documentation is english

[hoijui]

... and if not,
give a bad score, but with a very low weight

Use a natural language detection library for this,
feeding it all the clear-text extracted from all the Markdown files.
I found no such library for Nim, but here is one for rust:
https://crates.io/crates/lingua
... so maybe we should use it through CLI invocation as well?