Update DEVELOPMENT.md

Author: jinjingforever

DEVELOPMENT.md

@@ -1 +1,11 @@
-# Development notes
+# Development notes
+
+## Build app locally
+
+To successfully build and run the application through Android Studio, you need to configure it with your own HuggingFace Developer Application ([official doc](https://huggingface.co/docs/hub/oauth#creating-an-oauth-app)). This is required for the model download functionality to work correctly.
+
+After you've created a developer application:
+
+1. In [`AuthConfig.kt`](https://github.com/google-ai-edge/gallery/blob/main/Android/src/app/src/main/java/com/google/ai/edge/gallery/ui/common/AuthConfig.kt), replace the placeholders for `clientId` and `redirectUri` with the values from your HuggingFace developer application.
+
+1. In [`app/build.gradle.kts`](https://github.com/google-ai-edge/gallery/blob/c1b50e160a66d5ea2ec2d8d8e63088b3cc0761bc/Android/src/app/build.gradle.kts#L41-L44), modify the `manifestPlaceholders["appAuthRedirectScheme"]` value to match the redirect URL you configured in your HuggingFace developer application.