Mention the Code Review document in CONTRIBUTING, and add some clarifications to the code review document. I removed the paragraph describing bors delegation from CONTRIBUTING, as the code review document doesn't call for delegation to occur. Now the code review document tells owners to merge using bors. I added a pointer to the code review document to the CONTRIBUTING document. I think the code review document stands on its own, so I didn't combine them.

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index a992373..6f0974e 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md

@@ -1,12 +1,3 @@
-# PR Workflow
-
-We use the bors-ng bot to merge PRs. In short, when someone replies `bors r+`,
-your PR has been scheduled for final tests and will be automatically merged. If
-a maintainer replies `bors delegate+`, then you have been granted the authority
-to merge your own PR (usually this will happen if there are some trivial
-changes required). For a full list of bors commands,
-[see the bors documentation](https://bors.tech/documentation/).
-
 # Tests
 
 Our aim is to provide a number of tests to be safe from regression. Currently,
@@ -52,3 +43,8 @@
 [      OK ] GPIO read/write
 [      OK ] Test suite finished with state SUCCESS
 ```
+
+# PR Review Workflow
+
+Our code review practices are documented in our [Code Review](doc/CodeReview.md)
+document.

diff --git a/doc/CodeReview.md b/doc/CodeReview.md
index ff5c2dc..5b0995d 100644
--- a/doc/CodeReview.md
+++ b/doc/CodeReview.md

@@ -16,7 +16,9 @@
 The owners of `libtock-rs` (listed [below](#owners)) determine whether a PR is
 an upkeep PR or a significant PR. PRs should be merged by the `libtock-rs`
 owners rather than the PR's author. PRs authored by `libtock-rs` owners should
-be merged by a reviewer rather than their author.
+be merged by a reviewer rather than their author. In general, PRs should be
+merged using a `bors r+` command rather than the GitHub UI (see the [bors
+documentation](https://bors.tech/documentation/) for more information on bors).
 
 A PR may only be merged when all of the following are true:
 
@@ -25,6 +27,11 @@
 1. If the pull request is significant, a 7 day waiting period has passed since
    the PR was opened.
 
+We recommend that authors of significant PRs comment on the PR when they believe
+the above criteria have been satisfied (including the waiting period). This is
+primarily to remind the owners to merge the PR. Secondarily, it should help
+identify confusion about a PR review's status.
+
 ## Owners
 
 The owners of `libtock-rs` are: