update the readme.

Signed-off-by: wxywb <xy.wang@zilliz.com>

README.md

@@ -18,16 +18,20 @@ This operator extracts features for text with [data2vec](https://arxiv.org/abs/2
 
 Use the pre-trained model to generate a text embedding for the sentence "Hello, world.".
 
- *Write the pipeline in simplified style*:
+*Write a pipeline with explicit inputs/outputs name specifications:
 
 ```python
-import towhee
+from towhee.dc2 import pipe, ops, DataCollection
 
-towhee.dc(["Hello, world."]) \
-      .text_embedding.data2vec() \
-      .show()
+p = (
+    pipe.input('text')
+        .map('text', 'vec', ops.text_embedding.data2vec(model_name='facebook/data2vec-text-base'))
+        .output('text', 'vec')
+)
 
+DataCollection(p('Hello, world.')).show()
 ```
+<img src="./result.png" width="800px"/>
 
 
 <br />