nav tweaks for consistency & usability

[shawna-slh]

• SLH: Create an "Accessibility Fundamentals Overview" page similar to the others. Update index.md wai-fundamentals-overview#3
• SLH: Consider the title of "Evaluating Web Accessibility Overview" & the nav "Test & Evaluate", and the title of "W3C Accessibility Standards Overview" (for nav Standards/Guidelines)
• yatil: Make the first text in the secondary nav area link to the overview page (and remove "overview" link) -> Remove navigation header, use section header as navigation title instead of overview #154
• whoever: change "and" to "&" in overview page titles so it doesn't bug yatil ;-)

[yatil]

I can address #154 (and here bullet point 3) when the Accessibility Fundamentals Overview Page is ready. The other points have no impact on me making the change technically.

[shawna-slh]

I can address #154 (and here bullet point 3) when the Accessibility Fundamentals Overview Page is ready. The other points have no impact on me making the change technically.

Thanks! Done. (I'll QA is once preview available.)

[yatil]

Now I’m confused after I worked on this for a couple of hours today… Is it done or does it need QA?

Preview has been available since before your comment at w3c/wai-fundamentals-overview#3…

[yatil]

Here’s how it looks (Blue when on another page, you can view how it behaves in the https://wai-website-theme.netlify.com/ preview.)

[shawna-slh]

Preview took a little bit. I did quick spell check. That's good enough for now.

[yatil]

My parts of this issue are done.