Add Documentation on how to implement the stack in custom environments

Value Proposition

TBD

• https://squidfunk.github.io/mkdocs-material/

Acceptance Criteria

• how to create a custom repo and include the upstream sources
• how to override fabcity.hamburg domains
• architecture diagram

changed milestone to %INTERFACER M3.2 - FabCity OS Alpha-Release

added DevOps Fab City Software Kit labels

assigned to @swendel

Include Jaromils notes https://cloud.fabcity.hamburg/f/208580

changed the description