Proof read and flesh out editions docs

[iHiD]

Everything under https://exercism.lol/docs/using/editions is a stub and could do with some love. Make magic happen ✨

[jmh-git]

I believe, this sentence misses a word (added in bold): In 2019, we launched Exercism Research - a subsite of Exercism focussed on using our data and community to learn more about how we learn.

[jmh-git]

Typo (corrected in bold): However, as Exercism grew, the small-team aspects didn't fit with our larger mentoring platform, and so we separated that out into a seperate edition: Exercism Teams.

[kotp]

If you can @jmh-git you can provide a pull request.

[kotp]

exercism/exercism#6566 is asking fo rupdates on the editions docs, specifically teams.md