update the readme.

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

README.md

@@ -28,11 +28,11 @@ import towhee
 
 towhee.glob('./teddy.jpg') \
       .image_decode() \
-      .image_text_embedding.lightningdot(modality='image') \
+      .image_text_embedding.lightningdot(model_name='lightningdot_base', modality='image') \
       .show()
 
 towhee.dc(["A teddybear on a skateboard in Times Square."]) \
-      .image_text_embedding.lightningdot(modality='text') \
+      .image_text_embedding.lightningdot(model_name='lightningdot_base', modality='text') \
       .show()
 ```
 <img src="https://towhee.io/image-text-embedding/lightningdot/raw/branch/main/vec1.png" alt="result1" style="height:20px;"/>
@@ -45,12 +45,12 @@ import towhee
 
 towhee.glob['path']('./teddy.jpg') \
       .image_decode['path', 'img']() \
-      .image_text_embedding.lightningdot['img', 'vec'](modality='image') \
+      .image_text_embedding.lightningdot['img', 'vec'](model_name='lightningdot_base', modality='image') \
       .select['img', 'vec']() \
       .show()
 
 towhee.dc['text'](["A teddybear on a skateboard in Times Square."]) \
-      .image_text_embedding.lightningdot['text','vec'](modality='text') \
+      .image_text_embedding.lightningdot['text','vec'](model_name='lightningdot_base', modality='text') \
       .select['text', 'vec']() \
       .show()
 ```