Extend docs with registry mirror as workaround for custom images (tes…

…tcontainers#2452)

Add a link to registry mirror documentation in docker as a possibility when direct usage of docker hub is not allowed

Co-Authored-By: Kevin Wittek <kiview@users.noreply.github.com>

docs/features/configuration.md

@@ -45,6 +45,9 @@ Some companies disallow the usage of Docker Hub, but you can override `*.image`
 > **localstack.container.image = localstack/localstack**  
 > Used by LocalStack
 
+Another possibility is to set up a registry mirror in your environment so that all images are pulled from there and not directly from Docker Hub.
+For more information, see the [official Docker documentation about "Registry as a pull through cache"](https://docs.docker.com/registry/recipes/mirror/).
+
 ## Customizing Ryuk resource reaper
 
 > **ryuk.container.image = quay.io/testcontainers/ryuk:0.2.3**