Document Netlify deployments

Signed-off-by: Julius Volz <julius.volz@gmail.com>

README.md

@@ -52,6 +52,24 @@ make serve
 You should now be able to view the generated site at
 [http://localhost:3000/](http://localhost:3000).
 
+## Automatic Deployment
+
+This site is automatically deployed using [Netlify](https://www.netlify.com/).
+
+If you have the prerequisite access rights, you can view the Netlify settings here:
+
+* GitHub webhook notifying Netlify of branch changes: https://github.com/prometheus/docs/settings/hooks
+* Netlify project: https://app.netlify.com/sites/prometheus-docs
+
+Changes to the `master` branch are deployed to the main site at https://prometheus.io.
+
+Netlify also creates preview deploys for every pull request. To view these for a PR where all checks have passed:
+
+1. In the CI section of the PR, click on "Show all checks".
+2. On the "deploy/netlify" entry, click on "Details" to view the preview site for the PR.
+
+You may have to wait a while for the "deploy/netlify" check to appear after creating or updating the PR, even if the other checks have already passed.
+
 ## License
 
 Apache License 2.0, see [LICENSE](LICENSE).