Update documentation!

the documentation is still based on the old dasf-web framework that is not maintained and officially supported anymore. We need to update the documentation and particularly create sections about the following topics:

1. building frontends with dasf-web-components and dasf-messaging-typescript
2. how to use DASF for prototyping
3. how to secure and deploy for operational usage on HPC systems

all these questions are solved already, but I need to write it down...