add feature matrix

README.md

@@ -1,11 +1,13 @@
 # OpenTelemetry Lambda
+
 ![GitHub Java Workflow Status](https://img.shields.io/github/actions/workflow/status/open-telemetry/opentelemetry-lambda/ci-java.yml?branch%3Amain&label=CI%20%28Java%29&style=for-the-badge)
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 ## OpenTelemetry Lambda Layers
+
 The OpenTelemetry Lambda Layers provide the OpenTelemetry (OTel) code to export telemetry asynchronously from AWS Lambdas. It does this by embedding a stripped-down version of [OpenTelemetry Collector Contrib](https://github.com/open-telemetry/opentelemetry-collector-contrib) inside an [AWS Lambda Extension Layer](https://aws.amazon.com/blogs/compute/introducing-aws-lambda-extensions-in-preview/).
 
 Some layers include the corresponding OTel language SDK for the Lambda. This allows Lambdas to use OpenTelemetry to send traces and metrics to any configured backend.
@@ -18,12 +20,53 @@ Some layers include the corresponding OTel language SDK for the Lambda. This all
 * ### [.NET + Collector Lambda Layer](dotnet/README.md)
 * ### [Collector Lambda Layer](collector/README.md)
 
-
 ## FAQ
+
 * **What exporters/recievers/processors are included from the OpenTelemetry Collector?**
     > You can check out [the stripped-down collector's imports](https://github.com/open-telemetry/opentelemetry-lambda/blob/main/collector/lambdacomponents/default.go#L18) in this repository for a full list of currently included components.
 * **Is the Lambda layer provided or do I need to build it and distribute it myself?**
     > This repository does not provide pre-build Lambda layers. They must be built manually and saved in your AWS account. This repo has files to facilitate doing that. More information is provided in [the Collector folder's README](collector/README.md).
 
 ## Design Proposal
+
 To get a better understanding of the proposed design for the OpenTelemetry Lamda extension, you can see the [Design Proposal here.](docs/design_proposal.md)
+
+## Features
+
+The following is a list of features provided by the OpenTelemetry layers.
+
+### Custom Context Propagation
+
+Context can be propagated through various mechanisms (e.g. http headers (APIGW), message attributes (SQS), ...). In some cases, it may be required to pass a custom context propagation extractor in lambda through configuration, this feature allows this through Lambda instrumentation configuration.
+
+### Disable AWS Context propagation via environment variable
+
+The context propagation when Active Tracing is enabled uses the `_X_AMZN_TRACE_ID` environment variable present in the Lambda runtime. To disable this behaviour, implementations have added the `OTEL_LAMBDA_DISABLE_AWS_CONTEXT_PROPAGATION` environment variable which can be set to `true`.
+
+### Semantic conventions
+
+The Lambda language implementation follows the semantic conventions specified in the OpenTelemetry Specification.
+
+### Auto instrumentation
+
+The Lambda layer includes support for automatically instrumentation code via the use of instrumentation libraries.
+
+### Support matrix
+
+The table below captures the state of various features and their levels of support different runtimes.
+
+| Feature                    | Node | Python | Java | .NET | Go   | Ruby |
+| -------------------------- | :--: | :----: | :--: | :--: | :--: | :--: |
+| Custom Context Propagation |      |        |      |      |      |      |
+| Disable AWS Propagation    |      |        |      |      |      |      |
+| Semantic conventions       |      |        |      |      |      |      |
+| - Trace General            |      |        |      |      |      |      |
+| - Trace Incoming           |      |        |      |      |      |      |
+| - Trace Outgoing           |      |        |      |      |      |      |
+| - Metrics                  |      |        |      |      |      |      |
+| Auto Instrumentation       |      |        |      |      |      |      |
+
+The following are runtimes which are no longer or not yet supported by this repository:
+
+* Node.js 18 - not currently supported (see [#322](https://github.com/open-telemetry/opentelemetry-lambda/issues/322))
+* Node.js 12 - not [officially supported](https://github.com/open-telemetry/opentelemetry-js#supported-runtimes) by OpenTelemetry JS