add chainlit docker-based example

[edublancas]

we recently added docker-based examples for some of the frameworks that we officially support

streamlit example: https://github.com/ploomber/doc/tree/main/examples/streamlit/docker-based

this allows more flexibility for deployments, and we also added a note to the docs: https://docs.cloud.ploomber.io/en/latest/apps/streamlit.html

we should add a similar example for chainlit apps: https://github.com/ploomber/doc/tree/main/examples/chainlit

we have a sample chainlit Dockerfile in the cloud-backend repo

[edublancas]

fixed by #235