Introduce semantic versioning

[stas-at-ibm]

Description

Introduce semantic versioning, add documentation entry on how it is done in the project.

Technical Design

• [x] read articles
• [x] test versioning workflow
• [x] write docu
• [x] link semver spec in your readme
• [x] add pipeline step: validate git tag
• [x] add git tag and latest tag to docker image

Resources

• https://travishorn.com/semantic-versioning-with-git-tags-1ef2d4aeede6
• https://semver.org/
• https://dev.to/kouts/automated-versioning-and-package-publishing-using-github-actions-and-semantic-release-1kce
• https://github.com/marketplace/actions/action-for-semantic-release
• https://github.com/marketplace/actions/semantic-version
• https://github.com/marketplace/actions/git-semantic-version