Provide instructions for standalone deployment

[aahmed-se]

Build instructions to deploy for superset for demo purposes.

Ideally should be single tenant self contained docker image.
Provide for preconfigured connections, dashboard, user accounts or even no login via simple configs or env variables.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions. For admin, please label this issue .pinned to prevent stale bot from closing the issue.