Add info how to add a new trigger on a new project

README.md

@@ -57,6 +57,28 @@ We use [GitLab Pages][pages] to build and host this website. You can see
 A [job] is used to trigger a new build whenever tests run and pass on master
 branch of CE.
+To add a new trigger for another project:
+
+1. Go to https://gitlab.com/gitlab-com/doc-gitlab-com/triggers (you need Master
+   access) and copy the trigger value.
+1. Go to the project you will be triggering from and add a secret variable
+   named `DOCS_TRIGGER_TOKEN` with the value of the trigger you copied from the
+   previous step.
+1. Add the following job to the project's `.gitlab-ci.yml`:
+
+    ```yaml
+    # Trigger docs build
+    # https://gitlab.com/gitlab-com/doc-gitlab-com/blob/master/README.md#deployment-process
+    trigger_docs:
+      before_script: []
+      cache: {}
+      artifacts: {}
+      script:
+        - "curl -X POST -F token=${DOCS_TRIGGER_TOKEN} -F ref=master https://gitlab.com/api/v3/projects/38069/trigger/builds"
+      only:
+        - master
+    ```
+
 [contributing]: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#merge-request-guidelines
 [doc-styleguide]: https://docs.gitlab.com/ce/development/doc_styleguide.html
 [job]: https://gitlab.com/gitlab-org/gitlab-ce/blob/2c00d00ec1c39dbea0e0e54265027b5476b78e3c/.gitlab-ci.yml#L308-318