fix(readme): update contributors image (#13068)

The current image is too large to load.
see github.com/orgs/community/discussions/116471

Author: edison1105

README.md

@@ -44,7 +44,9 @@ Please make sure to read the [Contributing Guide](https://github.com/vuejs/core/
 
 Thank you to all the people who already contributed to Vue!
 
-<a href="https://github.com/vuejs/core/graphs/contributors"><img src="https://opencollective.com/vuejs/contributors.svg?width=890" /></a>
+<a href="https://github.com/vuejs/core/graphs/contributors"><img src="https://opencollective.com/vuejs/contributors.svg?width=890&limit=500" /></a>
+
+<sub>_Note: Showing the first 500 contributors only due to GitHub image size limitations_</sub>
 
 ## License