Navigation: convert About navigation to a dropdown

[agjohnson]

From #174 and chat conversations, the current "About" navigation link should be something clearer, while retaining the flow of the top navigation menu. The best option is likely making "About" a dropdown, and most likely renaming the menu title to a more specific phrase like "Product".

• Add dropdowns for desktop and mobile
• Move about to a new page

[agjohnson]

cc @ericholscher

This was the original plan for the menu item that was renamed to "Features". I'm still ±0 on "Product", but there is probably another word that fits well here too.

But I think even if we stick with "Product" the menu could be:

Product:
  - How Read the Docs works (this is the current "features" page, but was meant more as a overview page originally)
  - Features:
    - Building
    - Pull request previews
    - Authentication
    - etc
  - Supported tools:
    - Sphinx
    - Mkdocs
    - Unofficial tools

I think this helps solve focus of the existing "features" page and still gives us a reasonable menu item name for the top navigation. It also opens up the door to expanding navigation a great deal

[ericholscher]

Yea, I agree. This is a great place to focus on additional content 💯

Though I'd do s/Unnofficial/Custom or similar for marketing purposes :)

[agjohnson]

Started a draft PR at #221 but I didn't play around much with the content structure too much yet. It needs icons probably and the mobile menu is a bit broken by this too. Just putting it up for now as I end my day.

[ericholscher]

Good example here: https://www.cerbos.dev/

[agjohnson]

Yeah, this is a fairly common pattern, here are some others:

• https://about.gitea.com/
• https://about.gitlab.com/
• https://github.com/

To continue this work:

• I would limit the number of items in the top nav to two items, maybe three though that is starting to overload the top navigation especially on tablet viewport sizes
• There are some small visual tweaks needed with SUI, like adding a dropdown icon
• The PR above breaks mobile navigation menu, as the dropdown menus aren't stacking nicely. It's not clear if an FUI submenu solves this or not.