add usage

README.md

@@ -11,3 +11,23 @@ $ make init
 ```sh
 $ make update
 ```
+
+## Usage
+
+You can run this if you have:
+
+- your keystore as `ReVanced.keystore`
+- your apks stored in `APKs/`
+
+<!-- The password is the default of ReVanced Manager -->
+
+```sh
+java -jar revanced-cli.jar \
+    -a="APKs/XXX.apk" \
+    -b revanced-patches.jar \
+    --exclusive \
+    --experimental \
+    --keystore="ReVanced.keystore" \
+    --password="s3cur3p@ssw0rd" \
+    --out="revanced-app.apk"
+```