Add Full Text Search with Algolia to docs

[AnalyzePlatypus]

The current built-in search is terrible (title-only).

How am I supposed to find query error handling, for example?

Algolia offers free full-text search for open source projects, and they have first party VuePress integration.

It would be great if this useful library had first-rate Algolia search, especially as it's practically no work at all to implement.

(If I had write permissions, I'd add it myself)

Thanks!

[AnalyzePlatypus]

@Akryum , can I work on this?
(I'll need write permissions before Algolia will talk to me)