[repo] Add ReleaseNotes.md to include features shipped in stable release

OpenTelemetry.sln

@@ -18,6 +18,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		LICENSE.TXT = LICENSE.TXT
 		NuGet.config = NuGet.config
 		README.md = README.md
+		RELEASENOTES.md = RELEASENOTES.md
 		THIRD-PARTY-NOTICES.TXT = THIRD-PARTY-NOTICES.TXT
 		VERSIONING.md = VERSIONING.md
 	EndProjectSection
@@ -123,6 +124,9 @@ EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Benchmarks", "test\Benchmarks\Benchmarks.csproj", "{DE9130A4-F30A-49D7-8834-41DE3021218B}"
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "docs", "docs", "{7C87CAF9-79D7-4C26-9FFB-F3F1FB6911F1}"
+	ProjectSection(SolutionItems) = preProject
+		docs\README.md = docs\README.md
+	EndProjectSection
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "examples", "examples", "{2C7DD1DA-C229-4D9E-9AF0-BCD5CD3E4948}"
 	ProjectSection(SolutionItems) = preProject

RELEASENOTES.md

@@ -0,0 +1,53 @@
+# Release Notes
+
+This file contains highlights and announcements covering all components.
+For more details see `CHANGELOG.md` files maintained in the root source
+directory of each individual package.
+
+## 1.9.0
+
+* `Exemplars` are now part of the stable API! For details see: [customizing
+  exemplars
+  collection](https://github.com/open-telemetry/opentelemetry-dotnet/tree/main/docs/metrics/customizing-the-sdk#exemplars).
+
+* `WithLogging` is now part of the stable API! Logging, Metrics, and Tracing can
+  now all be configured using the `With` style and the builders finally have
+  parity in their APIs.
+
+## 1.8.0
+
+* `TracerProvider` sampler can now be configured via the `OTEL_TRACES_SAMPLER` &
+  `OTEL_TRACES_SAMPLER_ARG` envvars.
+
+* A new `UseOtlpExporter` cross-cutting extension has been added to register the
+  `OtlpExporter` and enable all signals in a single call.
+
+* `exception.type`, `exception.message`, `exception.stacktrace` will now
+  automatically be included by the `OtlpLogExporter` when logging exceptions.
+  Previously an experimental environment variable had to be set.
+
+## 1.7.0
+
+* Bumped the package versions of System.Diagnostic.DiagnosticSource and other
+  Microsoft.Extensions.* packages to `8.0.0`.
+
+* Added `net8.0` targets to all the components.
+
+* OTLP Exporter
+  * Updated to use `ILogger` `CategoryName` as the instrumentation scope for
+    logs.
+  * Added named options support for OTLP Log Exporter.
+  * Added support for instrumentation scope attributes in metrics.
+  * Added support under an experimental flag to emit log exception attributes.
+  * Added support under an experimental flag to emit log eventId and eventName.
+    attributes.
+
+* Added support for the
+  [IMetricsBuilder](https://learn.microsoft.com/dotnet/api/microsoft.extensions.diagnostics.metrics.imetricsbuilder)
+  API.
+
+* Added an experimental opt-in metrics feature to reclaim unused MetricPoints
+  which enables a higher number of unique dimension combinations to be emitted.
+  See [reclaim unused metric
+  points](https://github.com/open-telemetry/opentelemetry-dotnet/blob/32c64d04defb5c92d056fd8817638151168b10da/docs/metrics/README.md#cardinality-limits)
+  for more details.

build/RELEASING.md

@@ -203,6 +203,7 @@ Maintainers (admins) are needed to merge PRs and for the push to NuGet.**
     repository which opens a PR to update dependencies. Verify this PR was
     opened successfully.
 
- 8. Post an announcement in the [Slack
-    channel](https://cloud-native.slack.com/archives/C01N3BC2W7Q). Note any big
-    or interesting new features as part of the announcement.
+ 8. For stable releases, update [Release Notes](../RELEASENOTES.md) with any big
+    or interesting new features and then post an announcement in the [Slack
+    channel](https://cloud-native.slack.com/archives/C01N3BC2W7Q) with the same
+    information.

src/OpenTelemetry/CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+This file contains individual changes for the OpenTelemetry package.
+For highlights and announcements covering all components see: [Release Notes](../../RELEASENOTES.md).
+
 ## Unreleased
 
 * Added `OpenTelemetrySdk.Create` API for configuring OpenTelemetry .NET signals