docs: update README

Author: uerceg

README.md

@@ -173,6 +173,14 @@ Adjust.start(adjustConfig);
 
 Since August 1st 2014, apps in the Google Play Store must use the [Google Advertising ID](https://developer.android.com/google/play-services/id.html) to uniquely identify devices. To allow the Adjust SDK to use the Google Advertising ID, make sure to add latest version of [`play-services-ads-identifier`](https://mvnrepository.com/artifact/com.google.android.gms/play-services-ads-identifier?repo=google) AAR into the `Assets/Plugins/Android` folder of your Unity project.
 
+If you are using `Google External Dependency Manager` plugin, you can also add this dependecy by stating it inside of your `Dependencies.xml` file:
+
+```xml
+<androidPackages>
+    <androidPackage spec="com.google.android.gms:play-services-ads-identifier:18.0.1" />
+</androidPackages>
+```
+
 #### Testing for the Google advertising ID
 
 To check whether the Adjust SDK is receiving the Google advertising ID, start your app by configuring the SDK to run in `sandbox` mode and set the log level to `verbose`. After that, track a session or an event in the app and check the list of parameters recorded in the verbose logs. If you see the `gps_adid` parameter, our SDK has successfully read the Google advertising ID.
@@ -208,6 +216,14 @@ The Adjust post-build process makes sure that SDK will be able to capture the Go
 
 To add support for the Google Play Referrer API, download the latest [install referrer library](https://mvnrepository.com/artifact/com.android.installreferrer/installreferrer) AAR from Maven repository and place it into your `Plugins/Android` folder.
 
+If you are using `Google External Dependency Manager` plugin, you can also add this dependecy by stating it inside of your `Dependencies.xml` file:
+
+```xml
+<androidPackages>
+    <androidPackage spec="com.android.installreferrer:installreferrer:2.2" />
+</androidPackages>
+```
+
 #### <a id="qs-huawei-referrer-api"></a>Huawei Referrer API
 
 As of v4.21.1, the Adjust SDK supports install tracking on Huawei devices with Huawei App Gallery version 10.4 and higher. No additional integration steps are needed to start using the Huawei Referrer API.