Update typescript.md

Without <{}> TypeScript compiler shows this error:
Generic type 'NavigationContainerRef' requires 1 type argument(s).ts(2314)

Author: saeid-elio

versioned_docs/version-5.x/typescript.md

@@ -252,7 +252,7 @@ import { NavigationContainerRef } from '@react-navigation/native';
 
 // ...
 
-const navigationRef = React.useRef<NavigationContainerRef>(null);
+const navigationRef = React.useRef<NavigationContainerRef<{}>>(null);
 ```
 
 Example when using `React.createRef`: