docs(index.md): fix typo, spellchecker now passes

docs/index.md

@@ -211,7 +211,7 @@ For each React Native Firebase module, add the required [Expo Config Plugin](htt
 
 For iOS only, since `firebase-ios-sdk` requires `use_frameworks` please configure [expo-build-properties](https://docs.expo.dev/versions/latest/sdk/build-properties/#pluginconfigtypeios) and add the following entry to their `plugins` array in `app.json`:
 
-Here is an example `app.json` to enable the Firebase App, Auth and Crashlytics modules, the Service Account files for both mobile platforms and setting the applicatio ID to the example value of `com.mycorp.myapp` (change to match your own):
+Here is an example `app.json` to enable the Firebase App, Auth and Crashlytics modules, the Service Account files for both mobile platforms and setting the application ID to the example value of `com.mycorp.myapp` (change to match your own):
 
 ```json
 {