📝 Docs: Rephrase "New in ..." notices on versions to say "Since ..."

[JoshuaKGoldberg]

Documentation Request Checklist

• I have read and agree to Mocha's Code of Conduct and Contributing Guidelines
• I have searched for related issues and issues with the faq label, but none matched my issue.
• I want to provide a PR to resolve this

Overview

The docs on mochajs.org include a lot of notices like https://mochajs.org/#-watch-ignore-filedirectoryglob:

New in v7.0.0

v7.0.0 came out 4 years ago. We're on 10.x now. I don't think we need to keep any "New in" notices prior to 10.

Additional Info

No response

[voxpelli]

I like what Node.js does with their Since: 7.0.0, maybe keep them but change the wording to that?

[JoshuaKGoldberg]

Sure, works for me.

Out of curiosity: for versions > a few years old, what benefit do you see from keeping these around?

[voxpelli]

Same value as in Node, if one updates from an old version. Not very important to me though