docs: Add Docker remote host configuration

docs/custom_configuration/index.md

@@ -17,6 +17,18 @@ Testcontainers supports various configurations to set up your test environment.
 | `ryuk.container.image`      | `TESTCONTAINERS_RYUK_CONTAINER_IMAGE`      | The Ryuk (resource reaper) Docker image.                                                                                  | `testcontainers/ryuk:0.3.4` |
 | `hub.image.name.prefix`     | `TESTCONTAINERS_HUB_IMAGE_NAME_PREFIX`     | The name to use for substituting the Docker Hub registry part of the image name.                                          | -                           |
 
+## Configure remote container runtime
+
+To configure a remote container runtime, Testcontainers provides support for Docker's environment variables in addition to the properties file. During initialization, Testcontainers' auto-discovery feature detect and apply custom configurations including container runtimes. If you are running Docker on a remote host, you can configure it using either of the following methods:
+
+```console title="Properties File"
+docker.host=tcp://docker:2375
+```
+
+```console title="Environment Variable"
+DOCKER_HOST=tcp://docker:2375
+```
+
 ## Enable logging
 
 In .NET logging goes usually through the test framework. Testcontainers is not aware of the project's test framework and may not forward log messages to the right stream. The default implementation forwards log messages to the `Console` (respectively `stdout` and `stderr`) and `Debug`. The output should at least pop up in the IDE running tests in the `Debug` configuration. To override the default implementation, set the `TestcontainersSettings.Logger` property to an instance of an `ILogger` implementation.