Auto merge of #4971 - ehuss:overflow-checks-doc, r=alexcrichton
authorbors <bors@rust-lang.org>
Wed, 24 Jan 2018 02:36:53 +0000 (02:36 +0000)
committerbors <bors@rust-lang.org>
Wed, 24 Jan 2018 02:36:53 +0000 (02:36 +0000)
Add overflow-checks to reference documentation.

Fixes #4925.


Trivial merge