Add docs for container scanning config ui

doc/user/application_security/configuration/index.md

@@ -49,7 +49,9 @@ You can configure the following security controls:
   - Select **Configure with a merge request** to create a merge request with the changes required to
     enable Dependency Scanning. For more details, see [Enable Dependency Scanning via an automatic merge request](../dependency_scanning/index.md#enable-dependency-scanning-via-an-automatic-merge-request).
 - [Container Scanning](../container_scanning/index.md)
-  - Can be configured with `.gitlab-ci.yml`. For more details, read [Container Scanning](../../../user/application_security/container_scanning/index.md#configuration).
+  - Select **Configure with a merge request** to create a merge request with the changes required to
+    enable Container Scanning. For more details, see
+    [Enable Container Scanning through an automatic merge request](../container_scanning/index.md#enable-container-scanning-through-an-automatic-merge-request).
 - [Cluster Image Scanning](../cluster_image_scanning/index.md)
   - Can be configured with `.gitlab-ci.yml`. For more details, read [Cluster Image Scanning](../../../user/application_security/cluster_image_scanning/#configuration).
 - [Secret Detection](../secret_detection/index.md)

doc/user/application_security/container_scanning/index.md

@@ -253,6 +253,24 @@ images. To configure the images, set the `CS_ANALYZER_IMAGE` variable to the sta
 | Grype           | `registry.gitlab.com/security-products/container-scanning/grype:4-ubi` |
 | Trivy           | `registry.gitlab.com/security-products/container-scanning/trivy:4-ubi` |
 
+### Enable Container Scanning through an automatic merge request
+
+> [Introduced](https://gitlab.com/groups/gitlab-org/-/epics/6334) in GitLab 14.9.
+
+To enable Container Scanning in a project, create a merge request from the Security Configuration
+page:
+
+1. In the project where you want to enable Container Scanning, go to
+   **Security & Compliance > Configuration**.
+1. In the **Container Scanning** row, select **Configure with a merge request**.
+
+This automatically creates a merge request with the changes necessary to enable Container Scanning.
+To complete the configuration, review and merge this merge request.
+
+The configuration tool works best with no existing `.gitlab-ci.yml` file, or with a minimal
+configuration file. If you have a complex GitLab configuration file, it may not be parsed
+successfully and an error may occur.
+
 ### Overriding the container scanning template
 
 If you want to override the job definition (for example, to change properties like `variables`), you