Docs: add guide for exposing clickhouse

[MykalMachon]

Summary of issue

By default, the ClickHouse service is not exposed over the internet; it's only available on the Railway internal/private network. However, by using Railway's TCP Proxying feature you could easily expose the service over the public internet.

While I think the service being private is a good default, it does make sense to include a guide on making the service public using the aforementioned TCP proxying feature.

Specs and requirements

The docs for this should:

• Be in the README.md for this repo under "Additional Resources"
• Be formatted as a simple bulleted list with steps to exposing the service
• Go over what environment variables should be changed as part of exposing ClickHouse publicly
• Link to railway's docs on both TCP proxying and public/vs private services