Auto merge of #4695 - behnam:doc-book, r=alexcrichton
authorbors <bors@rust-lang.org>
Sat, 4 Nov 2017 14:47:48 +0000 (14:47 +0000)
committerbors <bors@rust-lang.org>
Sat, 4 Nov 2017 14:47:48 +0000 (14:47 +0000)
[doc/book] Change title to The Cargo Book

Also add "community’s" to description of crates.io, as Cargo now
supports multiple registries.


Trivial merge