doc: mention git-node in the collaborator guide

COLLABORATOR_GUIDE.md

@@ -21,6 +21,7 @@
  - [Deprecations](#deprecations)
  - [Involving the TSC](#involving-the-tsc)
 * [Landing Pull Requests](#landing-pull-requests)
+ - [Using `git-node`](#using-git-node)
  - [Technical HOWTO](#technical-howto)
  - [Troubleshooting](#troubleshooting)
  - [I Just Made a Mistake](#i-just-made-a-mistake)
@@ -454,6 +455,26 @@ Additionally:
 - All commits should be self-contained (meaning every commit should pass all
  tests). This makes it much easier when bisecting to find a breaking change.
 
+### Using `git-node`
+
+In most cases, using [the `git-node` command][git-node] of [`node-core-utils`][]
+should be enough to help you land a Pull Request. If you discover a problem when
+using this tool, please file an issue
+[to the issue tracker][node-core-utils-issues].
+
+Quick example:
+
+```text
+$ npm install -g node-core-utils
+$ git node land $PRID
+```
+
+If it's the first time you have ever use `node-core-utils`, you will be prompted
+to type the password of your GitHub account in the console so the tool can
+create the GitHub access token for you. If you do not want to do that, follow
+[the guide of `node-core-utils`][node-core-utils-credentials]
+to set up your credentials manually.
+
 ### Technical HOWTO
 
 Clear any `am`/`rebase` that may already be underway:
@@ -569,7 +590,8 @@ commit logs, ensure that they are properly formatted, and add
 
 <a name="metadata"></a>
 * Modify the original commit message to include additional metadata regarding
- the change process. ([`node-core-utils`][] fetches the metadata for you.)
+ the change process. (the [`git node metadata`][git-node-metadata] command
+ can generate the metadata for you.)
 
  * Required: A `PR-URL:` line that references the *full* GitHub URL of the
  original pull request being merged so it's easy to trace a commit back to
@@ -748,6 +770,10 @@ LTS working group and the Release team.
 [Stability Index]: doc/api/documentation.md#stability-index
 [Enhancement Proposal]: https://github.com/nodejs/node-eps
 [`--pending-deprecation`]: doc/api/cli.md#--pending-deprecation
+[git-node]: https://github.com/nodejs/node-core-utils/blob/master/docs/git-node.md
+[git-node-metadata]: https://github.com/nodejs/node-core-utils/blob/master/docs/git-node.md#git-node-metadata
 [git-username]: https://help.github.com/articles/setting-your-username-in-git/
 [`node-core-utils`]: https://github.com/nodejs/node-core-utils
 [TSC]: https://github.com/nodejs/TSC
+[node-core-utils-issues]: https://github.com/nodejs/node-core-utils/issues
+[node-core-utils-credentials]: https://github.com/nodejs/node-core-utils#setting-up-credentials