Document typical deployment cases

[yamalight]

There's currently a few typical use cases for exoframe - would be great to have those as step-by-step guides in docs.
Cases (to be extended):

• Basic project deployment with custom domain, env vars
• Deploying project to path instead of just domain name
• Deploying project that has db + service:
  • Basic deployment with compose (write down downsides)
  • "Optimal" deployment as two exoframe deployments (db as a separate thing via image field)