fix expo-iap link

Author: jaworek

src/docs/guides/library-compatibility/alternatives.md

@@ -12,7 +12,7 @@ The `expo-iap` library supports Meta Horizon OS billing:
 npm install expo-iap
 ```
 
-Follow the [expo-iap Horizon OS setup guide](https://hyochan.github.io/expo-iap/docs/getting-started/setup-horizon/).
+Follow the [expo-iap Horizon OS setup guide](https://hyochan.github.io/expo-iap/getting-started/setup-horizon).
 
 ### Use Cases