docs and examples imports update

docs/source/multi_gpu_training.mdx

@@ -4,10 +4,10 @@ This guide shows you how to train policies on multiple GPUs using [Hugging Face
 
 ## Installation
 
-First, ensure you have accelerate installed:
+`accelerate` is included in the `training` extra. Install it with:
 
 ```bash
-pip install accelerate
+pip install 'lerobot[training]'
 ```
 
 ## Training with Multiple GPUs