Update README

Signed-off-by: Jael Gu <mengjia.gu@zilliz.com>

README.md

@@ -16,7 +16,7 @@ As suggested, it is suitable to extract features at high level or warm up a larg
 
 ## Code Example
 
-Generate embeddings for the audio "test.wav". 
+Generate embeddings for the audio "test.wav".
 
 *Write the pipeline in simplified style*:
 
@@ -43,6 +43,7 @@ import towhee
           .audio_decode.ffmpeg['path', 'frames']()
           .runas_op['frames', 'frames'](func=lambda x:[y[0] for y in x])
           .audio_embedding.vggish['frames', 'vecs']()
+          .select['path', 'vecs']()
           .show()
 )
 ```