[fix] Update README

README.md

@@ -2,6 +2,24 @@
 
 Cobalt is a demo app for hybrid search with vector and surface search using [Ruri](https://huggingface.co/cl-nagoya/ruri-large), [BM25](https://github.com/dorianbrown/rank_bm25) and [Voyager](https://spotify.github.io/voyager/). The name cobalt is derived from the word 瑠璃 (Ruri), which refers to cobalt glass.
 
+## Usage
+
+```python
+import pandas as pd
+from model.search.hybrid import HybridSearchClient
+
+# load documents from CSV file.
+df = pd.read_csv("corpus.csv")
+
+# Initialize search client
+# Specify column name to be searched. e.g. "content"
+search_client = HybridSearchClient.from_dataframe(df, "content")
+
+# Search documents from a query
+results = search_client.search_top_n("Arashi's history")
+
+```
+
 ## Requirements
 
 - Python 3.10