update readme with dc2

README.md

@@ -17,16 +17,20 @@ This operator can compare two ordered sequences, then detect the range which fea
 
 
 ```python
-import towhee
+from towhee.dc2 import pipe, ops, DataCollection
 import numpy as np
 
 # simulate a video feature by 10 frames of 512d vectors.  
 videos_embeddings = np.random.randn(10,512)
 videos_embeddings = videos_embeddings / np.linalg.norm(videos_embeddings,axis=1).reshape(10,-1)
 
-towhee.dc['src','dest']([[videos_embeddings,videos_embeddings]]) \
-      .video_copy_detection.temporal_network[('src','dest'), ('range', 'range_score')]() \
-      .show()
+p = (
+    pipe.input('src', 'dest') \
+        .map(('src', 'dest'), ('range', 'range_score'), ops.video_copy_detection.temporal_network()) \
+        .output('src', 'dest', 'range', 'range_score')
+)
+
+DataCollection(p(videos_embeddings, videos_embeddings)).show()
 ```
 
 <img src="./tabular.png" alt="result" style="height:60px;"/>