Update README.md

Add instructions to build transformers from source.
After transformers will create a new version with the desired changes, we can remove this line and just add a minimal version requirement.

README.md

@@ -52,6 +52,12 @@ Granite Vision model is supported natively `transformers` from the `main` branch
 
 ### Usage with `transformers`
 
+First, make sure to build transormers from source following instructions [here](https://huggingface.co/docs/transformers/v4.48.2/en/installation#install-from-source): 
+```shell
+pip install git+https://github.com/huggingface/transformers
+```
+
+Then run the code:
 ```python
 from transformers import AutoProcessor, AutoModelForVision2Seq
 from huggingface_hub import hf_hub_download