Add documentation how to create CI job for "pass all requirements" test report

Create a CI job definition with semantic "I confirmed that requirements are met".

• it should be a manual job
• this job could be added into pipeline dynamically depending whether there are some open requirements in the project or not (this should be possible - &2859 (comment 328877704)), we could consider doing this in a second iteration though? 🤔
• it will produce a job artifact consumed by CI requirements report parser (TODO add an issue link), the content could be just a CSV file with single row representing that all requirements passed - e.g. *;passed - the reason is that this would be easy to extend in next iteration when we will trace specific tests (step 3)
• it will be up to users to add this job into gitlab CI YML file of their project, but we could add it as a non-blocking optional (allow_failure: true) job for gitlab project
• job sample should be included also in documentation

very roughly it might be something like:

confirm_requirements:
  stage: deploy
  script: "echo '*;passed;' > tmp/requirements.csv"
  when: manual
  artifacts:
    paths:
      - tmp/requirements.csv

Related to &2859 (closed) and specifically &2859 (comment 328030969)