Update README.md

Author: nakamuuu

README.md

@@ -1,5 +1,34 @@
 # Android Rectangle Detector
 
+[![](https://jitpack.io/v/smartbank-inc/android-rectangle-detector.svg)](https://jitpack.io/#smartbank-inc/android-rectangle-detector)
+
 A simple implementation of rectangle detector on Android using OpenCV.
 
 <img src="https://user-images.githubusercontent.com/12740720/137485630-4e1595e7-9655-4f52-9626-9e3c603b9907.png" width="320">
+
+## Download
+
+### Gradle
+
+Add it in your root build.gradle at the end of repositories:
+
+```groovy
+allprojects {
+    repositories {
+        ...
+        maven { url 'https://jitpack.io' }
+    }
+}
+```
+
+Add the dependency in your module's build.gradle:
+
+```groovy
+dependencies {
+    implementation "com.github.smartbank-inc:android-rectangle-detector:${latest_version}"
+}
+```
+
+## Requirements
+
+Android 8.0+ (API Level: 26+)