Remove Google surveillance included by default by mdbook

[aral]

After posting a copy of the book on my site, I was alerted that I was unknowingly contributing to giving Google eyes on the web and exposing my visitors to surveillance by Google/Alphabet, Inc. because mdbook apparently includes a bunch of Google surveillance by default (https://github.com/rust-lang-nursery/mdBook/search?utf8=%E2%9C%93&q=google&type=).

We should remove this from our build and not expose people to surveillance while reading the book.

[aral]

I‘ve now submitted a pull request for mdbook that, if/when merged, will serve web fonts locally and not hit Google’s servers:

rust-lang/mdBook#848

In the meanwhile, to create a Google-free version of The Dat Protocol book, you can use my fork:

https://github.com/aral/mdBook

My copy on https://ar.al/the-dat-protocol (which includes #19), serves all assets entirely first-party.

[yoshuawuyts]

@aral Oh yeah, that PR looks really good. Would be really neat if it landed on mdbook!