Docs: Update predefined_variables.md to fix anchor

doc/ci/variables/predefined_variables.md

@@ -36,7 +36,7 @@ future GitLab releases.**
 | `CI_COMMIT_TAG`                         | 9.0    | 0.5    | The commit tag name. Present only when building tags. |
 | `CI_COMMIT_TITLE`                       | 10.8   | all    | The title of the commit - the full first line of the message |
 | `CI_CONFIG_PATH`                        | 9.4    | 0.5    | The path to CI config file. Defaults to `.gitlab-ci.yml` |
-| `CI_DEBUG_TRACE`                        | all    | 1.7    | Whether [debug tracing](../README.md#debug-tracing) is enabled |
+| `CI_DEBUG_TRACE`                        | all    | 1.7    | Whether [debug tracing](README.md#debug-tracing) is enabled |
 | `CI_DEPLOY_PASSWORD`                    | 10.8   | all    | Authentication password of the [GitLab Deploy Token][gitlab-deploy-token], only present if the Project has one related.|
 | `CI_DEPLOY_USER`                        | 10.8   | all    | Authentication username of the [GitLab Deploy Token][gitlab-deploy-token], only present if the Project has one related.|
 | `CI_DISPOSABLE_ENVIRONMENT`             | all    | 10.1   | Marks that the job is executed in a disposable environment (something that is created only for this job and disposed of/destroyed after the execution - all executors except `shell` and `ssh`). If the environment is disposable, it is set to true, otherwise it is not defined at all. |