Merge branch 'document-clair-trace-cs-env-var' into 'master'

Document CLAIR_TRACE var for Container Scanning

See merge request gitlab-org/gitlab!28322

doc/user/application_security/container_scanning/index.md

@@ -170,6 +170,7 @@ using environment variables.
 | Environment Variable           | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | Default                                                                                                         |
 | ------                         | ------                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | ------                                                                                                          |
 | `KLAR_TRACE`                   | Set to true to enable more verbose output from klar.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | `"false"`                                                                                                       |
+| `CLAIR_TRACE`                  | Set to true to enable more verbose output from the clair server process.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | `"false"`                                                                                   |
 | `DOCKER_USER`                  | Username for accessing a Docker registry requiring authentication.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | `$CI_REGISTRY_USER`                                                                                             |
 | `DOCKER_PASSWORD`              | Password for accessing a Docker registry requiring authentication.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | `$CI_REGISTRY_PASSWORD`                                                                                         |
 | `CLAIR_OUTPUT`                 | Severity level threshold. Vulnerabilities with severity level higher than or equal to this threshold will be outputted. Supported levels are `Unknown`, `Negligible`, `Low`, `Medium`, `High`, `Critical` and `Defcon1`.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | `Unknown`                                                                                                       |