Use Proselint for linting language on docs

Problem to solve

My English isn't perfect, and it's probably never going to be. This isn't a problem, usually, as reviewers will review English as well. However, things can be missed that can be statically checked, removing some of the review burden.

Further details

For documentation, and maybe commit messages, use static linters to improve the choice of words in our English and improve our documentation with it.

Proposal

Use proselint in our CI pipeline.

What does success look like, and how can we measure that?

Better documentation, automatically detect improvements of words and sentences in English.

Links / references

https://github.com/amperser/proselint/

/cc @rymai @axil

Edited by Achilleas Pipinellis