Include documentation regarding xray-lambda propagator (#1678)

* Include documentation regarding xray-lambda propagator

* Update java/README.md

Co-authored-by: Tyler Benson <[email protected]>

---------

Co-authored-by: Tyler Benson <[email protected]>

Author: arun-annamalai

java/README.md

@@ -59,6 +59,19 @@ For any other library, such as OkHttp, you will need to include the correspondin
 from the [instrumentation project](https://github.com/open-telemetry/opentelemetry-java-instrumentation) and
 modify your code to initialize it in your function.
 
+### Configuring Context Propagators
+
+#### If you emit your traces to AWS X-Ray (instead of a third-party service) and have enabled X-Ray Active Tracing
+Please use the following environment variable for your lambda:
+`OTEL_PROPAGATORS=tracecontext,baggage,xray-lambda`
+
+#### If you emit your traces to another system besides AWS X-Ray (Default Setting)
+The following propagators are configured by default, but you can use this environment variable to customize it:
+`OTEL_PROPAGATORS=tracecontext,baggage,xray`
+
+
+For more information please read: https://opentelemetry.io/docs/specs/semconv/faas/aws-lambda
+
 ## Building
 
 To build the Java Agent layer, run