Improve local setup

[maxceem]

• Kafka is accessible from inside docker-compose and outside, which let us start all the services inside docker-compose, but if we need to modify one, we just stop inside docker and run outside where can modify it, but it still connects to all other services inside docker-compose
• use single container for all postgresql databases
  • now all the services may use the same port 5432 and don't have to be additionally configured
  • docker compose became lighter as we use one container for 3 databases instead of 3 containers
• Steps to run locally are simplified and clarified in the README
• Added guide regarding Project Service Architecture:
  • overview diagram
  • how Elasticsearch indexing works
  • Kafka messages structure