Fix nav menus for responsive

[jrday]

When you reduce horizontal window size, eventually the left-nav of docs get collapsed into a hamburger menu. A couple of issues with how it works right now:

1. The left nav gets collapsed while the right nav (in-page outline) remains expanded.
2. The collapsed hamburger menu is not very visible.

Once reduced further, the right menu goes away, and we get this:

Fixes:

• [ ] Remove the right-side menu entirely. It doesn't really serve an important purpose (it's an outline of the current page) and takes screen real estate to do so. Let's just nix it.
• [ ] Make the hamburger menu easier to find. Currently, it's just too subtle

[benjordan]

Requested changes completed and pushed.

[gjtorikian]

Confirmed fixed!