Update README.md

adding a comment that cuda kernels needs to be build

README.md

@@ -24,6 +24,9 @@ tokenizer = AutoTokenizer.from_pretrained(model_id)
 model     = HQQModelForCausalLM.from_quantized(model_id)
 
 #Optional: set backend/compile
+#You will need to install CUDA kernels apriori
+# git clone https://github.com/mobiusml/hqq/
+# cd hqq/kernels && python setup_cuda.py install
 from hqq.core.quantize import *
 HQQLinear.set_backend(HQQBackend.ATEN_BACKPROP)