Fixing event handler names in code sample in readme.md

This pull request fixes a code sample in the readme.md file. The previous code had incorrect event handler names (onCreateAnnotation, onUpdateAnnotation, and onDeleteAnnotation were all set to onCreateAnnotation). This update corrects the event handler names to their respective functions. Now, the code functions as intended.

### Changes Made
- Fixed event handler names in the code snippet.
- Replaced "onCreateAnnotation" with "onUpdateAnnotation" and "onDeleteAnnotation" at the appropriate locations.

README.md

@@ -41,8 +41,8 @@ window.onload = function() {
       config={config} 
       annotations={annotations} 
       onCreateAnnotation={onCreateAnnotation} 
-      onUpdateAnnotation={onCreateAnnotation} 
-      onDeleteAnnotation={onCreateAnnotation} />,
+      onUpdateAnnotation={onUpdateAnnotation} 
+      onDeleteAnnotation={onDeleteAnnotation} />,
     document.getElementById('app')
   );