Auto merge of #4047 - boxofrox:update-bin-docs, r=alexcrichton
authorbors <bors@rust-lang.org>
Mon, 15 May 2017 14:08:19 +0000 (14:08 +0000)
committerbors <bors@rust-lang.org>
Mon, 15 May 2017 14:08:19 +0000 (14:08 +0000)
Update docs: cargo does not build src/bin/*.rs when toml contains [[bin]

Update docs per #4013.

Does it make sense to also mention this behavior in the [Configuring a target](http://doc.crates.io/manifest.html#configuring-a-target) section?


Trivial merge