UI feedback when search doesn't yield any results

[mortenpi]

I just spent a couple of minutes debugging why the search doesn't work after it couldn't find a (long) query. I tried with like 1-2 character queries, but nothing showed up then either, so it felt that the search was broken.¹

Could the dropdown should open as soon as anything gets typed into the search box, and say either "type more characters" or "no results for this query" if it can't show anything useful?

Footnotes

1. It looks like you need to type in 3 characters before search results get shown? https://github.com/JuliaComputing/MultiDocumenter.jl/blob/0eeb757500fec7a485e0f426632056327017c81c/flexsearch/gensearch.js#L14 ↩