Bug fix: toggle sidebar open when moving to new section

[ttarsi]

Context:

A nit, but I've seen this is the case on any vocs site:

1. on the last page of a section, e.g. TwoSlash here:

2. At the bottom of the page, click next section (Config):

3. Config page opens, but the API section is still collapsed, so I can't see the page that I'm on in the sidebar

Proposed Solution:

Toggle a section open when a user opens a page within that section