Update README.md

Fix the import error

README.md

@@ -2631,7 +2631,8 @@ python -m pip install -U sentence-transformers
 
 ```python
 from sentence_transformers import SentenceTransformer
-from sentence_transformers.util import cos_sim, quantize_embeddings
+from sentence_transformers.util import cos_sim
+from sentence_transformers.quantization import quantize_embeddings
 
 # 1. Specify preffered dimensions
 dimensions = 512