Add links from top-level README to other READMEs.

Asked Gemini to add links to more specific READMEs from the top-level README to help developers understand the structure of the app.

Author: donovanfm

README.md

@@ -47,16 +47,15 @@ The project is organized into several modules and directories:
 -   `app/`: Contains the main Android application code.
     -   `src/main/`: Source code and resources for the main application.
         -   `java/`: Kotlin/Java source files.
-            -   `com/google/android/samples/socialite/`: The main package for the application.
-                -   `data/`: Data sources, repositories, and related logic.
-                -   `model/`: Data models and entities.
-                -   `ui/`: UI components, screens, and view models.
-                    -   `camera/`: Code related to the in-app camera feature.
-                    -   `chat/`: Code for the chat list and individual chat screens.
-                    -   `settings/`: Code for the settings screen.
-                    -   `timeline/`: Code for the timeline screen.
-                    -   `videoedit/`: Code for the video editing screen.
-                -   `util/`: Utility classes and helper functions.
+            -   `com/google/android/samples/socialite/`: The main package for the application. See the [README](app/src/main/java/com/google/android/samples/socialite/README.md) for more details.
+                -   `data/`: Data sources, repositories, and related logic. See the [README](app/src/main/java/com/google/android/samples/socialite/data/README.md) for more details.
+                -   `model/`: Data models and entities. See the [README](app/src/main/java/com/google/android/samples/socialite/model/README.md) for more details.
+                -   `ui/`: UI components, screens, and view models. See the [README](app/src/main/java/com/google/android/samples/socialite/ui/README.md) for more details.
+                    -   `camera/`: Code related to the in-app camera feature. See the [README](app/src/main/java/com/google/android/samples/socialite/ui/camera/README.md) for more details.
+                    -   `chat/`: Code for the chat list and individual chat screens. See the [README](app/src/main/java/com/google/android/samples/socialite/ui/chat/README.md) for more details.
+                    -   `settings/`: Code for the settings screen. See the [README](app/src/main/java/com/google/android/samples/socialite/ui/home/settings/README.md) for more details.
+                    -   `timeline/`: Code for the timeline screen. See the [README](app/src/main/java/com/google/android/samples/socialite/ui/home/timeline/README.md) for more details.
+                    -   `videoedit/`: Code for the video editing screen. See the [README](app/src/main/java/com/google/android/samples/socialite/ui/videoedit/README.md) for more details.
         -   `res/`: Application resources (layouts, drawables, values, etc.).
         -   `assets/`: Static assets like images and shaders.
     -   `build.gradle.kts`: Gradle build file for the app module.

app/src/main/java/com/google/android/samples/socialite/ui/home/timeline/README.md

@@ -1,6 +1,6 @@
 # Timeline Module
 
-This directory contains the code for the timeline screen of the SociaLite application. This screen displays a vertical feed of all photos and videos shared across all chat threads.
+This directory contains the code for the timeline screen of the SociaLite application. This screen displays a vertical feed of all photos and videos shared across all chat threads. This screen uses `PreloadManagerWrapper.kt` which builds on ExoPlayer's [DefaultPreloadManager](https://developer.android.com/reference/androidx/media3/exoplayer/source/preload/DefaultPreloadManager) to enable smooth vertical scrolling between media items.
 
 -   **Timeline UI:** Jetpack Compose composables (e.g., `TimelineScreen.kt`) for displaying the list of media items (photos and videos) in a scrollable feed. This involves displaying the media content and potentially some associated information like the sender or timestamp.
 -   **ViewModel Logic:** A ViewModel (e.g., `TimelineViewModel`) to manage the state and logic for the timeline screen. This ViewModel is responsible for fetching the list of media items from the data layer and exposing it to the UI.