Remove blog and move content to relevant spots in docs

[rianrietveld]

• I've checked the existing issues for this change

URL
page URL at https://wpaccessibility.org/

Reason:

If we blog, it could better be in make/a11y or on developer.wordpress.org/news/. Because that has a way higher exposior. And a latest blog post from 2 years ago is pathetic.

We can integrate the 3 blogposts we have now in the current content.

The work

• Move Why accessibility should be your next priority, insights from WordCamp Europe 2025 as a submenu item in Accessibility for your business.
• Move I have a question, but I don’t have WhatsApp! as as submenu item of Content and images.
• Move Accessible error messages in forms as as submenu item of Accessible web forms. Check for duplicates in current content.
• Check and update internal links.
• Keep the blog functionality in the software, just don't use it for now.
• Remove link to blog in the footer., replace by a link to Accessibility Overlays.