Add instructions for downloading shaded variants

Author: psx95

gcp-auth-extension/README.md

@@ -50,6 +50,8 @@ For more information on Extensions, see the [documentation here](https://github.
 
 > [!IMPORTANT]
 > Make sure to download the 'shaded' variant of the Authentication Extension for use with OpenTelemetry Java auto-instrumentation agent. The shaded version is available under the classifier name `shadow`.
+> 
+> See instructions for [Downloading Shaded JAR](#downloading-shaded-jar) below.
 
 Below is a snippet showing how to add the extension to a Java application using the Gradle build system.
 
@@ -83,6 +85,21 @@ application {
 }
 ```
 
+#### Downloading Shaded JAR
+
+You can download the shaded JAR for Google Cloud Authentication Extension from the following link -
+
+```text
+https://repo1.maven.org/maven2/io/opentelemetry/contrib/opentelemetry-gcp-auth-extension/<VERSION>/opentelemetry-gcp-auth-extension-<VERSION>-shadow.jar
+```
+
+Replace `<VERSION>` with the version you wish to download. For instance, shaded
+variant for `v1.44.0-alpha`, will be found at -
+
+`https://repo1.maven.org/maven2/io/opentelemetry/contrib/opentelemetry-gcp-auth-extension/1.44.0-alpha/opentelemetry-gcp-auth-extension-1.44.0-alpha-shadow.jar`
+
+*Note: Typically, you would want to use the most recent version of the extension.*
+
 ### Without OpenTelemetry Java agent
 
 This extension can be used without the OpenTelemetry Java agent by leveraging the [OpenTelemetry SDK Autoconfigure](https://github.com/open-telemetry/opentelemetry-java/blob/main/sdk-extensions/autoconfigure/README.md) module.\