Merge branch 'docs-add-review-apps-doc-to-ci-index-ee' into 'master'

Docs: add Review Apps link to list of CI/CD topics

See merge request gitlab-org/gitlab-ee!9937

doc/ci/README.md

@@ -61,6 +61,7 @@ into more features:
 | [Connecting GitLab with a Kubernetes cluster](../user/project/clusters/index.md)                       | Integrate one or more Kubernetes clusters to your project.                                                                   |
 | [ChatOps](chatops/README.md)                                                                           | Trigger CI jobs from chat, with results sent back to the channel.                                                            |
 | [Interactive web terminals](interactive_web_terminal/index.md)                                         | Open an interactive web terminal to debug the running jobs.                                                                  |
+| [Review Apps](review_apps/index.md)                                                                    | Configure GitLab CI/CD to preview code changes in a per-branch basis.                                                        |
 | [Deploy Boards](../user/project/deploy_boards.md) **[PREMIUM]**                                        | Check the current health and status of each CI/CD environment running on Kubernetes.                                         |
 | [GitLab CI/CD for external repositories](ci_cd_for_external_repos/index.md) **[PREMIUM]**              | Get the benefits of GitLab CI/CD combined with repositories in GitHub and BitBucket Cloud.                                   |
 | [Protected environments](environments/protected_environments.md) **[PREMIUM]**                         | Ensure that only people with the right privileges can deploy to an environment.                                              |