updat docs

Author: Profesor08

website/docs/en/config/server/open.mdx

@@ -33,6 +33,16 @@ export default {
 };
 ```
 
+- Prevent to open any page:
+
+```ts title="rsbuild.config.ts"
+export default {
+  server: {
+    open: false,
+  },
+};
+```
+
 - Open the specified page:
 
 ```ts title="rsbuild.config.ts"