Fix submenu to expand when visiting page directly.

[andrew]

When directly visiting a top level section (like Community) on the new docs beta (i.e. clicking from offsite or pasting https://docs-beta.ipfs.io/community/ directly into your address bar), the left hand menu doesn't expand for the highlighted section:

I would expect it to be expanded in the same was as if I clicked on the "Community" link in the menu:

I happens for all the top level sections, not just Community, but it does work as expected for sub-sections like Community >> IRC

[cwaring]

Good catch, I'll try to patch this up in the next round of menu refactors!

[jessicaschilling]

Also for context, see https://github.com/ipfs/docs/issues/389 -- we'll be making future changes to the nav overall that, while they don't address what you've brought up in this issue, do speak to overall nav evolution. Ideally we'd get this submenu concern addressed either before, or in parallel, with the work that closes #265.

[johnnymatthews]

Just tried this on the VuePress docs site and it doesn't seem to be an issue there, so this is likely something that we've changed.