GitLab: "stageless" pipeline

- vis https://about.gitlab.com/blog/2021/08/24/stageless-pipelines/

content/docs/start/gitlab.md

@@ -61,16 +61,14 @@ Here, we'll walk through a tutorial to start using CML on GitLab.
    into a new file `.gitlab-ci.yml` and save.
 
    ```yaml
-   stages:
-     - cml_run
-
-   cml:
-     stage: cml_run
+   train-model:
      image: iterativeai/cml:0-dvc2-base1
      script:
        - pip3 install -r requirements.txt
        - python train.py
-
+   create-cml-report:
+     needs: train-model
+     script:
        - cat metrics.txt >> report.md
        - cml publish confusion_matrix.png --md >> report.md
        - cml send-comment report.md

content/docs/usage.md

@@ -59,17 +59,14 @@ and CML set up on an Ubuntu LTS base for convenience.
 The key file in any GitLab CI/CD project is `.gitlab-ci.yml`:
 
 ```yml
-# .gitlab-ci.yml
-stages:
-  - Train model
-cml:
-  stage: Train model
+train-model:
   image: iterativeai/cml:0-dvc2-base1
   script:
     - pip3 install -r requirements.txt
     - python train.py
-
-    # Create CML report
+create-CML-report:
+  needs: train-model
+  script:
     - cat metrics.txt >> report.md
     - cml publish confusion_matrix.png --md >> report.md
     - cml send-comment report.md