add link for JAR download (#29922)

Co-authored-by: cecilia saixue watt <cecilia.watt@datadoghq.com>

Author: gary-huang

content/en/llm_observability/setup/sdk/java.md

@@ -21,7 +21,7 @@ You can install and configure tracing of various operations such as workflows, t
 
 ### Prerequisites
 
-1. Download the `dd-trace-java` JAR.
+1. Download the [`dd-trace-java` JAR][5].
 
 2. LLM Observability requires a Datadog API key (see [the instructions for creating an API key][1]).
 
@@ -546,3 +546,5 @@ public class MyJavaClass {
 [2]: /llm_observability/terms/
 [3]: /getting_started/tagging/
 [4]: /llm_observability/setup/auto_instrumentation/?tab=java
+[5]: https://s3.us-east-1.amazonaws.com/dd-trace-java-builds/llmobs-java-sdk-integration/dd-java-agent.jar
+