add changelog

src/OpenTelemetry.Instrumentation.Http/CHANGELOG.md

@@ -2,6 +2,22 @@
 
 ## Unreleased
 
+* Updated `http.request.method` to match specification guidelines.
+  * For activity, request method will be set on an additional tag
+    `http.request.method.original` will be added if the method does not belong
+    to one of the [known
+    values](https://github.com/open-telemetry/semantic-conventions/blob/v1.22.0/docs/http/http-spans.md#:~:text=http.request.method%20has%20the%20following%20list%20of%20well%2Dknown%20values)
+    and `http.request.method` will be set to `_OTHER`.
+  * For metrics, `http.request.method` on `http.client.request.duration` metric
+    will be set to `_OTHER` if the original method does not belong to one of the
+    [known
+    values](https://github.com/open-telemetry/semantic-conventions/blob/v1.22.0/docs/http/http-spans.md#:~:text=http.request.method%20has%20the%20following%20list%20of%20well%2Dknown%20values)
+
+  `http.request.method` is set on `http.client.request.duration` metric or
+  activity when `OTEL_SEMCONV_STABILITY_OPT_IN` environment variable is set to
+  `http` or `http/dup`.
+  ([#5003](https://github.com/open-telemetry/opentelemetry-dotnet/pull/5003))
+
 ## 1.6.0-beta.2
 
 Released 2023-Oct-26