Auto merge of #2815 - alexcrichton:lets-add-some-docs, r=brson
authorbors <bors@rust-lang.org>
Wed, 6 Jul 2016 18:16:00 +0000 (11:16 -0700)
committerGitHub <noreply@github.com>
Wed, 6 Jul 2016 18:16:00 +0000 (11:16 -0700)
Document the [replace] section

Thought I did this before, but apparently forgot!


Trivial merge