Update naming for "about" pages across website.

[edonehoo]

Is this a new page or a change to an existing one?
Change to a few pages

Describe the enhancement
"About" pages across PF.org aren't accessible with VO, because they all just say "About". Updated page nav headings to be unique and more descriptive.

[andrew-ronaldson]

I discussed this with @edonehoo and although it can feel repetitive we could do About + name (About extensions). Seems like a small enough fix for this VO change