[racket] Additional cached index for documentation?

> Probably it should be a new document along the lines of
> "scribblings/main/[user/]search.scrbl" (in the "racket-index" package)
> or an extra output of those documents.
>
> And probably you want to generate a mapping from symbols to xref tags,
> since `xref-tag->path+anchor` can convert a tag to a URL relatively
> efficiently (by way of "docindex.sqlite").

Did someone go ahead and do this?

Because a few weeks ago I noticed this got _much_ faster on Racket
HEAD. Well under 1 second. Which is awesome.