Update settings and docs for multiuser mode

[itutu-tienday]

• Contents

  • Update settings
  • Add docker-compose.dev.multiuser.yml to use multiuser mode in docker.
  • Applied patch to Dockerfile (fixed unavailability of alembic command)
  • Update docs
    • Updated multiuser mode setup documentation. ( host_for_multiuser/setup.md )
    • Added clear setup instructions for docker.
    • Corrected other errors and confusing parts.

• Testing

  • Confirmed that "docker + multiuser mode" can be setup by following the documentation and using above docker-compose yaml.
  • Converted results to HTML (sphinx) also confirmed.