fix: typos in using_custom_app_widget.md

doc/configurations/using_custom_app_widget.md

@@ -1,14 +1,14 @@
 # Using Custom App Widget
 
-This project use some adaptive widgets like `AdaptiveTextSelectionToolbar` which require the following delegates:
+This project uses some adaptive widgets like `AdaptiveTextSelectionToolbar` which require the following delegates:
 
 1. Default Material Localizations delegate
 2. Default Cupertino Localizations delegate
-3. Defualt Widgets Localizations delegate
+3. Default Widgets Localizations delegate
 
-You don't need to include those since there are defined by default
- but if you are using Custom app or you are overriding the `localizationsDelegates` in the App widget
-then please make sure it's including those:
+You don't need to include those since they are defined by default
+ but if you are using a Custom app or you are overriding the `localizationsDelegates` in the App widget
+then please make sure it includes those:
 
 ```dart
 localizationsDelegates: const [
@@ -18,7 +18,7 @@ localizationsDelegates: const [
 ],
 ```
 
-And you might need more depending on your use case, for example if you are using custom localizations for your app, using custom app widget like `FluentApp` from [FluentUI]
+You might need more depending on your use case, for example, if you are using custom localizations for your app, using a custom app widget like `FluentApp` from [FluentUI]
 which will also need
 
 ```dart
@@ -31,4 +31,6 @@ localizationsDelegates: const [
 
 Note: In the latest versions of `FluentApp` you no longer need to add the `localizationsDelegates` but this is just an example, for more [info](https://github.com/bdlukaa/fluent_ui/pull/946)
 
-There are additonal notes in [Localizations](./localizations_setup.md) page
+There are additional notes on the [Localizations](./localizations_setup.md) page
+
+[FluentUI]: https://pub.dev/packages/fluent_ui