updated README

experimental/packages/opentelemetry-propagator-aws-xray-lambda/README.md

@@ -3,63 +3,18 @@
 [![NPM Published Version][npm-img]][npm-url]
 [![Apache License][license-image]][license-image]
 
-The OpenTelemetry Propagator for AWS X-Ray Lambda provides HTTP header propagation for systems that are using AWS `X-Amzn-Trace-Id` format.
-This propagator translates the OpenTelemetry SpanContext into the equivalent AWS header format, for use with the OpenTelemetry JS SDK.
-`TraceState` is currently not propagated.
-
-## Status
-
-| Maturity                                  | [Component Owner](../../.github/component_owners.yml) | Compatibility         |
-| ----------------------------------------- | ----------------------------------------------------- | --------------------- |
-| [Stable](../../../CONTRIBUTING.md#stable) | @carolabadeer                                         | API 1.0+<br/>SDK 1.0+ |
-
-## Installation
-
-```sh
-npm install --save @opentelemetry/propagator-aws-xray-lambda
-```
+The OpenTelemetry Propagator for AWS X-Ray Lambda provides propagation based on the X-Ray `_X_AMZN_TRACE_ID` environment
+variable in addition to the AWS X-Ray HTTP headers. This propagator should be used only for an AWS Lambda instrumentation.
 
 ## Usage
 
-In the [global tracer configuration file](https://opentelemetry.io/docs/instrumentation/js/getting-started/nodejs/#setup), configure the following:
-
-```js
-const { NodeTracerProvider } = require('@opentelemetry/sdk-trace-node');
-const { AWSXRayPropagator } = require('@opentelemetry/propagator-aws-xray');
-// ...
-
-const provider = new NodeTracerProvider();
-
-// Set the global trace context propagator to use X-Ray formatted trace header
-provider.register({
-  propagator: new AWSXRayPropagator()
-});
-```
+The preferred method for using this propagator is by using the `OTEL_PROPAGATORS` environment variable. For more details,
+see the [semantic conventions specification for AWS Lambda](https://github.com/open-telemetry/semantic-conventions/blob/main/docs/faas/aws-lambda.md).
 
 ## Propagator Details
 
-Example header:`X-Amzn-Trace-Id: Root=1-5759e988-bd862e3fe1be46a994272793;Parent=53995c3f42cd8ad8;Sampled=1`
-
-The header consists of three parts: the root trace ID, the parent ID and the sampling decision.
-
-### Root - The AWS X-Ray format trace ID
-
-* Format: (spec-version)-(timestamp)-(UUID)
-  * spec_version - The version of the AWS X-Ray header format. Currently, only "1" is valid.
-  * timestamp - 32-bit number in base16 format, corresponds to the first 8 characters of the OpenTelemetry trace ID. Note, while X-Ray calls this timestamp, for the purpose of propagation it is opaque and any value will work.
-  * UUID - 96-bit random number in base16 format, corresponds to the last 10 characters of the OpenTelemetry trace ID.
-
-Root is analogous to the [OpenTelemetry Trace ID](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/overview.md#spancontext), with some small format changes.
-For additional reading, see the [AWS X-Ray Trace ID](https://docs.aws.amazon.com/xray/latest/devguide/xray-api-sendingdata.html#xray-api-traceids) public documentation.
-
-### Parent - The ID of the AWS X-Ray Segment
-
-* 64-bit random number in base16 format. Populated from the [OpenTelemetry Span ID](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/overview.md#spancontext).
-
-### Sampled - The sampling decision
-
-* Defined in the AWS X-Ray specification as a tri-state field, with "0", "1" and "?" as valid values. Only "0" and "1" are used in this propagator. If "?", a new trace will be started.
-* Populated from the [OpenTelemetry trace flags](https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/overview.md#spancontext).
+The propagator extracts context from the `_X_AMZN_TRACE_ID` environment variable, except when there is already another 
+context active. It also automatically uses the [AWS X-Ray propagator](https://github.com/open-telemetry/opentelemetry-js-contrib/tree/main/propagators/opentelemetry-propagator-aws-xray).
 
 ## Useful links