Fix docker settings docs for custom parent images (#4332)

Author: schustmi

docs/book/how-to/containerization/containerization.md

@@ -420,6 +420,11 @@ The available package installers are:
 
 Full documentation for how `uv` works with PyTorch can be found on the Astral Docs website [here](https://docs.astral.sh/uv/guides/integration/pytorch/). It covers some of the particular gotchas and details you might need to know.
 
+{% hint style="info" %}
+If you're using `uv` and specify a custom parent image or Dockerfile that does not have an activated virtual environment, you need to pass `python_package_installer_args={"system": None}` in your DockerSettings so that
+`uv` installs the packages for the Python system installation. Depending on the parent image, you might also need to include `"break-system-packages": None` in the installer args as well to make it work.
+{% endhint %}
+
 ## Private PyPI Repositories
 
 For packages that require authentication from private repositories:

docs/book/user-guide/tutorial/distributed-training.md

@@ -47,6 +47,7 @@ from zenml.config import DockerSettings
 
 docker = DockerSettings(
     parent_image="pytorch/pytorch:2.1.0-cuda12.1-cudnn8-runtime",
+    python_package_installer_args={"system": None},
     requirements=["zenml", "torchvision"]
 )
 
@@ -111,6 +112,7 @@ Use the same CUDA image as above **plus** add Accelerate to the requirements:
 ```python
 DockerSettings(
     parent_image="pytorch/pytorch:2.1.0-cuda12.1-cudnn8-runtime",
+    python_package_installer_args={"system": None},
     requirements=["zenml", "accelerate", "torchvision"]
 )
 ```