Add deprecation note to Dynatrace metrics exporter (#1141)

opentelemetry-dynatrace/README.md

@@ -2,32 +2,43 @@
 
 [splash]: https://raw.githubusercontent.com/open-telemetry/opentelemetry-rust/main/assets/logo-text.png
 
-# OpenTelemetry Dynatrace
+# Dynatrace
 
-[`Dynatrace`] integration for applications instrumented with [`OpenTelemetry`].
+[Dynatrace](https://www.dynatrace.com/integrations/opentelemetry) supports native
+OpenTelemetry protocol (OTLP) ingest for traces, metrics and logs.
+All signals can be sent directly to Dynatrace via **OTLP protobuf over HTTP**
+using the built-in OTLP/HTTP Exporter available in the OpenTelemetry Rust SDK.
+More information on configuring your Rust applications to use the OTLP exporter can be found in the
+[Dynatrace documentation](https://www.dynatrace.com/support/help/shortlink/otel-wt-rust).
 
+## Dynatrace OpenTelemetry Metrics Exporter for Rust 
+
+![Static Badge](https://img.shields.io/badge/status-deprecated-orange)
 [![Crates.io: opentelemetry-dynatrace](https://img.shields.io/crates/v/opentelemetry-dynatrace.svg)](https://crates.io/crates/opentelemetry-dynatrace)
 [![Documentation](https://docs.rs/opentelemetry-dynatrace/badge.svg)](https://docs.rs/opentelemetry-dynatrace)
 [![LICENSE](https://img.shields.io/crates/l/opentelemetry-dynatrace)](./LICENSE)
 [![GitHub Actions CI](https://github.com/open-telemetry/opentelemetry-rust/workflows/CI/badge.svg)](https://github.com/open-telemetry/opentelemetry-rust/actions?query=workflow%3ACI+branch%3Amain)
 [![Slack](https://img.shields.io/badge/slack-@cncf/otel/rust-brightgreen.svg?logo=slack)](https://cloud-native.slack.com/archives/C03GDP0H023)
 
-## Overview
+> **Warning**
+> Dynatrace supports native OpenTelemetry protocol (OTLP) ingest for traces, metrics and logs.
+> Therefore, the proprietary Dynatrace OpenTelemetry metrics exporter is deprecated in favor of exporting via OTLP/HTTP.
+>
+> The exporter is still available but after the end of 2023, no support, updates, or compatibility with newer OTel versions will be provided.
+>
+> Please refer to the [migration guide](https://www.dynatrace.com/support/help/shortlink/migrating-dynatrace-metrics-exporter-otlp-exporter#migrate-applications) for instructions on how to migrate to the OTLP HTTP exporter, as well as reasoning and benefits for this transition.
+>
+> For an example on how to configure the OTLP exporter in a Rust application, check out the [Rust integration walk-through](https://www.dynatrace.com/support/help/shortlink/otel-wt-rust) page in the Dynatrace documentation.
+
+### Overview
 
 [`OpenTelemetry`] is a collection of tools, APIs, and SDKs used to instrument,
 generate, collect, and export telemetry data (metrics, logs, and traces) for
 analysis in order to understand your software's performance and behavior. This
 crate provides additional propagators and exporters for sending telemetry data
 to [`Dynatrace`].
 
-> **Warning**
-> This exporter is deprecated.
-> Dynatrace supports ingesting Traces and Metrics natively via OTLP, and therefore these should be sent directly to Dynatrace via **OTLP protobuf over HTTP** using the built-in [`opentelemetry-otlp`] exporter instead.
-> See the [Dynatrace documentation for Rust] and the [Dynatrace documentation for ingesting metrics via OTLP] for details.
-
-[Dynatrace documentation for ingesting metrics via OTLP]: https://www.dynatrace.com/support/help/shortlink/send-metrics-via-otlp-exporter
-
-## Exporter features
+### Exporter features
 
 * **Metrics** - Ingest metric data to Dynatrace using the [Dynatrace Metrics ingestion protocol].
 
@@ -45,15 +56,15 @@ state of the OpenTelemetry SDK for Rust.
 [Dynatrace documentation for Rust]: https://www.dynatrace.com/support/help/shortlink/opent-rust
 [`open-telemetry/opentelemetry-rust`]: https://github.com/open-telemetry/opentelemetry-rust
 
-### Examples
+#### Examples
 
 The examples directory contains an [advanced example](../examples/dynatrace) 
 showing the ingestion of trace data and metric data together.
 
 [`opentelemetry-otlp`]: https://crates.io/crates/opentelemetry-otlp
 [`opentelemetry-dynatrace`]: https://crates.io/crates/opentelemetry-dynatrace
 
-## Performance
+### Performance
 
 For optimal performance, a batch exporter is used. You can enable the `rt-tokio` 
 feature flag to use the [`tokio`] runtime, or enable the `rt-async-std` feature 
@@ -63,7 +74,7 @@ you automatically.
 [`tokio`]: https://tokio.rs
 [`async-std`]: https://async.rs
 
-## Choosing an HTTP client
+### Choosing an HTTP client
 
 The HTTP client that this exporter will use can be overridden with feature 
 flags. By default the `reqwest-client` feature flag is enabled which will use 
@@ -82,7 +93,7 @@ You can also configure your own http client implementation using the `HttpClient
 [`isahc`]: https://docs.rs/isahc/latest/isahc/
 [`surf`]: https://docs.rs/surf/latest/surf/
 
-## WebAssembly
+### WebAssembly
 
 WebAssembly support can be enabled with the `wasm` feature flag.