minor nit: section tracking within documentation

[andrewkmin]

Extremely minor, but I noticed that once you navigate to a subsection on https://chiru-labs.github.io/ERC721A/#/erc721a, you then become "anchored" to it such that if you want to click to jump to that same subsection later, clicks will be rendered useless (though you can refresh to jump back to that subsection if you'd like).

(one) proposed solution: dynamically update the URL based on the subsection you're currently viewing

See the following video/gif for a brief visualization of the issue:

[Vectorized]

docsifyjs/docsify#1780

Let’s wait a while and see if docsify has a solution to it.