ENH: Update Navigation Bar Organization

[mdefende]

What would you like to see added?

As of now, the navigation bar seems cluttered where all of the documentation for Cheaha, Cloud, etc is grouped with Account Management, Help, etc. It would be helpful to break these out into actual sections using the navigation.sections theme feature in MkDocs. I'm including a before image as well as a mockup of an after image below for comparison

Before:

After:

[wwarriner]

I very much like this in principle. I think we looked into this once before and there was something that held us back at the time, but I can't recall what. If you want to put in a draft PR it'd be good for us (and the rest of the team) to do some A/B testing to see what's preferred.