Remove open pi patch and use custom transformer branch for now

docs/source/pi0.mdx

@@ -21,44 +21,13 @@ As described by Physical Intelligence, while AI has achieved remarkable success
 
 ## Installation Requirements
 
-⚠️ **Warning**: This policy requires patching the Hugging Face `transformers` library.
-
-### Prerequisites
-
-1. Ensure you have the exact version installed:
+1. Install LeRobot by following our [Installation Guide](./installation).
+2. Install Pi0 dependencies by running:
 
    ```bash
-   pip show transformers
+   pip install -e ".[pi]"
    ```
 
-   It must be version **4.53.2**.
-
-2. Apply the custom patches:
-   ```bash
-   cp -r ./src/lerobot/policies/pi0/transformers_replace/* \
-     $(python -c "import transformers, os; print(os.path.dirname(transformers.__file__))")
-   ```
-
-### What the patches do:
-
-- Support the **AdaRMS optimizer**
-- Correctly control the precision of activations
-- Allow the KV cache to be used without updates
-
-**Important Notes:**
-
-- This permanently modifies your `transformers` installation
-- The changes survive reinstalls unless you explicitly remove the patched files or recreate the environment
-
-### Restoring Clean State
-
-To undo the patches and restore a clean state:
-
-```bash
-pip uninstall transformers
-pip install transformers==4.53.2
-```
-
 ## Training Data and Capabilities
 
 π₀ is trained on the largest robot interaction dataset to date, combining three key data sources: