Provide a more detailed architecture description

[h4uges]

To help new developers get started and to establish a common understanding of the architecture within the development team, a more detailed architecture description is needed.

The documentation should provide information about ...

• which modules exist (on package/project level)
• and for each module ...
  • its purpose/function
  • its provided interfaces/functionality
  • its ensured invariants
  • its depencencies
• how typical use cases are solved by Vitruv and which modules are involved

Also concepts which are spread across many modules should be explained in the documentation.