Switchted the docs to `maven-thymeleaf-skin:1.1.2`
* Upgraded `maven-thymeleaf-skin` to `1.1.1` and adjusted the configuration
* Upgraded `maven-site-plugin` to version `3.21.0`
* Upgraded `maven-thymeleaf-skin` to version `1.1.2`
* Added the prefix `/projects` to the URIs of the generated site
* Switched the linking for all old projects to the refined path
* Added a `Dockerfile` for building the project
* Added missing versions and refined the pathes for old versions