Update README to reflect recent work
Before raising this MR, consider whether the following are required, and complete if so:
- Documentation update(s)
No unit tests or metrics because you can't usefully gather metrics or add unit tests to a README update.
This MR updates the README to reflect recent work. The previous update (!554 (merged)) was only merged a couple of weeks ago, but my calendar says its time for a new MR to be made, and we've merged a reasonable amount of work in the intervening period.
We should merge !562 (merged) before this really, so that the content is technically correct.