Docs: write first part of the user guide

[developer3evg]

After scripting tasks are done we need to update README.md and create first part of the user guide to explain how to run the service.

Also under this task other automation that is left can be done

After this task, the service should be ready to run for initial try

[developer3evg]

Blocked by:

• Config wizard #4
• CD: create a script to set up ubuntu machine #3
• CD: set up api gateway #2
• https://github.com/Evgsoft/instant-swap/issues/27
• CD: create docker compose #5