Fix typo in README.md (#626)

README.md

@@ -127,7 +127,7 @@ If we want to remove seen items during training, we need to provide `TRAIN_SET`
 
 ## Efficient retrieval with ANN search
 
-One important aspect of deploying recommender model is efficient retrieval via Approximate Nearest Neighor (ANN) search in vector space. Cornac integrates several vector similarity search frameworks for the ease of deployment. [This example](tutorials/ann_hnswlib.ipynb) demonstrates how ANN search will work seamlessly with any recommender models supporting it (e.g., matrix factorization).
+One important aspect of deploying recommender model is efficient retrieval via Approximate Nearest Neighbor (ANN) search in vector space. Cornac integrates several vector similarity search frameworks for the ease of deployment. [This example](tutorials/ann_hnswlib.ipynb) demonstrates how ANN search will work seamlessly with any recommender models supporting it (e.g., matrix factorization).
 
 | Supported Framework | Cornac Wrapper | Example |
 | :-----------------: | :------------: | :-----: |