Resolve "Create documentation template"

Related issues

Add documentation template for a deskription of:

• Structure of the project
• API and Model
• Database Model
• Core Framework and Technologies

Acceptance criteria

• Implemented code changes don't diverge from the related issue.
• Only released versions of dependencies are used (i.e. no snapshot versions).
• Pipeline still works.
• GitLab issue is up-to-date.

If necessary, the following sections have been updated:

• Readme.md
• Documentation

Proposed squash commit message

Add documentation template for a deskription of:

• Structure of the project
• API and Model
• Database Model
• Core Framework and Technologies

Closes #53 (closed)