Update deployment flow docker compose
Created by: JeanPaulSG
Updated deployment flow for docker compose based on demo and discussion with SMEs in test plan. Added contextualising information, made prerequisites clear, made outcome clear, created linear path through process. https://github.com/sourcegraph/product-education/issues/28
Test plan
Language check by @blvckcoffee or @dulanism Technical accuracy check by @caugustus-sourcegraph or @kevinwojo or @briemcnally