[Docs site] Keep the menu nav section of currently viewed page expanded

[Adam Stankiewicz]

As is, when you visit a Paragon docs site page, the associated menu nav section is collapsed:

To improve docs site usability, we should ensure the containing section of the viewed page stays expanded:

Tasks

Beta Give feedback

1. Ensure the section containing the currently viewed page on the Paragon docs site is persistently expanded such that users know which section they are currently in.
2. Ensure the currently page in the collapsible menu section receives some "active" styling. Perhaps bold font?

[Peter Kulko]

PR: #2791