feat: update README to correct link for gradio_app to point to English version

projects/README.md

@@ -3,7 +3,7 @@
 ## Project List
 
 - Projects compatible with version 2.0:
-  - [gradio_app](./gradio_app/README_zh-CN.md): Web application based on Gradio
+  - [gradio_app](./gradio_app/README.md): Web application based on Gradio
 
 - Projects not yet compatible with version 2.0:
   - [web_api](./web_api/README.md): Web API based on FastAPI