Extend the `release:` keyword to support assets links in yaml

Release notes

Users can now use the release keyword to add assets to the release

Problem to solve

Extends the release: keyword to support asset links

Intended users

• Rachel (Release Manager)
• Sasha (Software Developer)

User experience goal

The user should be able to create releases and attach files to them in a single .gitlab-ci.yml release job.

Proposal

Extend the release: keyword to support assets links.

release:
  stage: release
  only: tags
  script:
    - make changelog | tee release_changelog.txt
  release:
    name: Release $CI_TAG_NAME
    description: ./release_changelog.txt
    assets:
      links:
        - name: cool-app.zip
          url: http://my.awesome.download.site/1.0-$CI_COMMIT_SHORT_SHA.zip
        - url: http://my.awesome.download.site/cool-app.exe