Suggestion: Remove https://pa11y.org/news/ or tweak, because it is very outdated

[HenrikBengtsson]

Hello, if someone visits https://pa11y.org/news/, there's great risk that they'll immediately conclude that this is a dead project. The most recent entry is for:

• 15 Feb 2018: Pa11y 5.0.0

I'd recommend to remove https://pa11y.org/news/, or alternatively, just point to the CHANGELOG files under each GitHub repo, e.g.

• pa11y CLI CHANGELOG
• pa11y CI CHANGELOG
• pa11y Dashboard CHANGELOG
• pa11y Webservice CHANGELOG