Update README.md

README.md

@@ -31,7 +31,7 @@ The model is compatible with Milvus Vector DB and is very easy to use:
 
 First, install the pymilvus library
 ```shell
-pip install pymilvus
+pip install pymilvus[model]
 ```
 
 The model can then be used to encode pairs of text and find the similarity between their representations