Redesign 'docs-nav`

[francisrupert]

Since we're currently aiming to build our non-Production-quality Demo JS as vanilla as possible, we should attemp to remove jQuery as an fsa-style dependency.

It's currently used primarily for src/js/components/docs-nav.js, which is probably simple enough to rebuild without jQ.

Low priority to start with, and could be tasked to either @bignamehere or @francisrupert.

[francisrupert]

UPDATE: 10/23 I've renamed this issue from "Convert docs-nav to Vanilla JS" to "Redesign 'docs-nav`"

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Actually, let's hold on this one. It initially was designed prior to the "Components" section, which hasn't scaled well.

I'm pretty sure this issue will be renamed to something like "Redo Kitchen Sink Nav." First obvious possibility is vertical on the side. We should avoid over-designing or over-scripting it; it's just meant to be a raw listing of everything in this CSS Framework.