add more doc using test container

[sebastianwessel]

          ### Note for Private Registry Users:

If you're using a private registry, you’ll need to configure Testcontainers to pull the Ryuk image from your internal registry. You can do this by creating a .testcontainers.properties file in your user directory (windows: e.g., C:/Users/YourUsername/.testcontainers.properties) with the following configuration:

ryuk.container.image = yourregistry.com/ryuk:0.3.3

This ensures Testcontainers pulls the Ryuk image from your registry, which is necessary for container cleanup.

See here for more details

Originally posted by @jascenc1 in #60 (comment)