Update wp-now documentation

[ironnysh]

What?

Updating the wp-now README file.

Why?

Some information was outdated or missing.

See details in this issue.

Testing Instructions

Review the text :-)

[ironnysh]

Thanks, @flexseth!

[ironnysh]

Cheers, @flexseth, and thanks for the review.

the docs will most likely mature in time.

Sure, just important to remember the distinction between the docs and the README 😄 especially while the current setup (Docusaurus) remains.

Going to try to track changes and keep a log

Not sure if it covers both repos (wordpress-playground and playground-tools), but @adamziel recently set up a cool automatic changelog that's also available on the official docs.

[adamziel]

I left one note but it looks great to me otherwise, thank you so much @ironnysh! CC wp-now folks: @sejas @wojtekn

[ironnysh]

@adamziel @sejas -- I think it's ready

[sejas]

Beautiful! Thanks for your hard work @ironnysh 🙏