update readme

Signed-off-by: junjie.jiang <junjie.jiang@zilliz.com>

README.md

@@ -1,2 +1,51 @@
-# milvus-client
+# ANN Search Operator: Milvus
 
+*author: junjie.jiangjjj*
+
+<br />
+
+## Desription
+Search embedding in [Milvus](https://milvus.io/), **please make sure you have inserted data to Milvus Collection**.
+
+<br />
+
+
+
+## Code Example
+
+> Please make sure you have inserted data into Milvus, refer to [ann_insert.milvus_client](https://towhee.io/ann-insert/milvus-client) and [load the collection](https://milvus.io/docs/v2.1.x/load_collection.md) to memory.
+
+
+```python
+from towhee.dc2 import pipe, ops
+
+p = pipe.input('vec') \
+    .map('vec', ('id', 'score'), ops.ann_insert.milvus_client(host='127.0.0.1', port='19530', collection_name='textdb')) \
+    .output('id', 'score')
+
+# call pipeline
+p(vec_data)
+```
+
+```python
+from towhee.dc2 import pipe, ops
+
+# search additional info url:
+
+p = pipe.input('vec') \
+    .map('vec', ('id', 'score', 'url'), ops.ann_insert.milvus_client(host='127.0.0.1', port='19530', collection_name='textdb', output_fields=['url'])) \
+    .output('id', 'score', 'url')
+```
+
+<br />
+
+
+
+## Factory Constructor
+
+Create the operator via the following factory method:
+
+***ann_search.milvus_client(host='127.0.0.1', port='19530', collection_name='textdb')***
+
+
+<br />