[Doc] Add llama2 android documentation

This patch adds llama2 android documentation.

Signed-off-by: Yelin Jeong <[email protected]>

android/README.md

@@ -7,3 +7,8 @@ This guide is suitable for normal application developers.
 
 * __Android Platform Guide__: If you are going to build Android rootFS from scratch for NNStreamer, then refer to [this guide](https://github.com/nnstreamer/nnstreamer-example/tree/master/android/android_platform_guide.md).
 This guide is _only_ suitable for Android platform developers or system guys.
+
+Also, we provide a [single APK integration](https://github.com/nnstreamer/nnstreamer-android) of NNStreamer and ML API.
+This application is a solution for on-device Machine Learning Operations (MLOps) and provides end-points to ML task.
+
+* __Android App using MLOps Solution__: If you want to make an Android Application without dependencies such as `aar`, then refer to [this guide](/android/kotlin_app/README.md).

android/kotlin_app/README.md

@@ -0,0 +1,74 @@
+# Android Application Examples using MLOps Solution
+
+## Prerequisite
+
+We assume that you already have experienced Android application developments with Android Studio.
+
+ * Host PC:
+   * OS: Ubuntu 20.04 / 22.04 x86_64 LTS
+   * Android Studio: Ubuntu version
+ * Target Device:
+   * CPU Architecture: ARM 64bit (aarch64)
+   * Android SDK: Min version 34
+   * [nnstreamer-android application](https://github.com/nnstreamer/nnstreamer-android/blob/main/documentation/getting_started.md#building-the-android-app-with-llama2) is installed.
+
+## Build example
+
+We provide Kotlin example which runs an LLM task.
+
+#### Cloning the GitHub Repository
+
+To build example application, you need to clone the repository.
+
+```bash
+$ git clone https://github.com/nnstreamer/nnstreamer-example
+
+$ ls nnstreamer-example/android/kotlin_app/llama2/
+app  build.gradle.kts  gradle  gradle.properties  gradlew  gradlew.bat  local.properties  settings.gradle.kts
+$ cd nnstreamer-example/android/kotlin_app/llama2
+```
+
+#### Building the Android App using Gradle
+
+In the example application's directory, `Gradle Wrapper` files have already been generated. You can
+build apk file as follows.
+
+```bash
+$ ./gradlew build
+
+> Task :app:compileReleaseKotlin
+...omitted...
+
+$ find app -name "*.apk"
+app/build/outputs/apk/debug/app-debug.apk
+app/build/outputs/apk/release/app-release-unsigned.apk
+```
+
+##### Running the App on the Android Device
+
+The Android device can use `adb` to install and run the app.
+
+```bash
+$ cd ${HOME}/Android/Sdk/platform-tools
+$ ls adb
+adb
+
+$ ./adb devices
+List of devices attached
+R3CW90D8TNR	device
+
+$ ./adb install ${HOME}/nnstreamer-example/android/kotlin_app/llama2/app/build/outputs/apk/debug/app-debug.apk
+Success
+
+$ ./adb shell am start ai.nnstreamer.example.llama2/ai.nnstreamer.example.llama2.MainActivity
+Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=ai.nnstreamer.example.llama2/.MainActivity }
+```
+
+If you can see the same user interface as the following screenshot, the Android app has been
+successfully installed and launched on the device.
+
+![Android Device Ready](img/ready.jpeg)
+
+If you enter the first part of the sentence in the input prompt and press the button, the llama2 model will complete the latter part.
+
+![Android Device Run](img/run.jpeg)