Create documentation

[kbkk]

Main README:

• [ ] Rush.js setup instructions / quick guide
• [x] Tree list with packages / services & links to their readme
• [ ] Roadmap (libraries to be written, decomposing to microservices)

Monolith README:

• [ ] Why start with a monolith?
• [ ] Architecture description / drawings
• [ ] Describe components under monolith's Core/ dir

General guides:

• [ ] Building a CI/CD workflow
• [ ] Cloud deployment considerations