add apidoc job

# Job from go2scale hub --> hub.go2scale.io

documentation:

  image:

    name: node:12.18.3-alpine3.12

    entrypoint: [""]

  stage: build

  variables:

    - APIDOC_CONFIG: ''

    - APIDOC_OUTPUT_PATH: './public'

  script:

    - npm install apidoc -g

    - apidoc --verbose -c $APIDOC_CONFIG -o $APIDOC_OUTPUT_PATH

  artifacts:

    when: always

    expose_as: "Documentation"

    paths:

      - public/

  rules:

    - if: '$DOCUMENTATION_DISABLE'

      when: never