Update README.md, fix function in demo

README.md

@@ -38,7 +38,7 @@ import matplotlib.pyplot as plt
 
 dataset = load_dataset("minwoosun/CholecSeg8k", trust_remote_code=True)
 
-def display_image(image_index):
+def display_image(dataset, image_index):
     '''Display the image and corresponding three masks.'''
     
     fig, axs = plt.subplots(2, 2, figsize=(10, 10))
@@ -57,7 +57,7 @@ def display_image(image_index):
     
     plt.show()
 
-display_image(800) # video index from 0 to 8079
+display_image(dataset, 800) # video index from 0 to 8079
 ```
 ![example image](example.png)