Allow CLI-searching the whole set

[klntsky]

Currently, docs-search CLI does not allow to search the whole set -- that's a problem, because docs-search gives better results when used via the CLI.

It is possible to make some sort of script to locally git checkout gh-pages branch of this repo and run docs-search on the generated docs.jsons, thus removing the need to acme-build locally.

[klntsky]

That means that we should upload docs.jsons to gh-pages, too. These files are ~30MB total.

OR docs-search should be extended with ability to use the generated indices in CLI mode (as for now only the web app uses these). The app should load them all at once to achieve the same level of results quality.