Fix link to feature flags example plugin (#196960)

Fixes link to code example in GH

packages/core/feature-flags/README.mdx

@@ -20,7 +20,7 @@ One example of invalid use cases are settings used during the `setup` lifecycle
 if an HTTP route is registered or not. Instead, you should always register the route, and return `404 - Not found` in the route 
 handler if the feature flag returns a _disabled_ state.  
 
-For a code example, refer to the [Feature Flags Example plugin](../../../examples/feature_flags_example)
+For a code example, refer to the [Feature Flags Example plugin](https://github.com/elastic/kibana/blob/main/examples/feature_flags_example/README.md)
 
 ## Registering a feature flag