Enhanced side bar search widget

[starbelly]

Currently, the search widget on the sidebar is the stock widget provided out of the box via docsearch.js. Doing some quick research it seems the idea behind the search widget provided by docsearch.js is primarily to get a site up and going with minimal to zero js/ts hacking required.

That's a great way to bootstrap but it has some limitations. It doesn't appear easy or possible to extend the widget anymore with docsearch v3, though perhaps more research is required.

It may be that we need to "fork" the widget to add the functionality we'd like to see on erlang.org. Below are a few enhancements we'd like to see :

Preview

On agolia's site we can see a nice side preview of a document as can be seen below :

## More results

While it's great to get all the results possible in the widget, it may be a better UX to limit the results and provide a link to the new search page added in #41 . This is also a nice to have as after clicking such a link, someone could bookmark the search. An example of this can be seen on docsearch's own page (show below) :

[starbelly]

Update @garazdawi figured out how to do the more search results link (#47), with that more digging is required before forking, as I have feeling the customization can be done with docsearch.js's widget.