update changelog to show otlphttp as replacement

.chloggen/deprecate_sapmexporter.yaml

@@ -15,7 +15,17 @@ issues: [36028]
 # (Optional) One or more lines of additional information to render under the primary note.
 # These lines will be padded with 2 spaces and then inserted directly into the document.
 # Use pipe (|) for multiline entries.
-subtext:
+subtext: |
+  The SAPM exporter is deprecated and will be removed in the next major release. 
+  Please use the `otlphttp` exporter with the following configuration and update your 
+  pipeline configuration accordingly:
+  ```yaml
+    exporters:
+        otlphttp:
+            traces_endpoint: "${INGEST_URL}/v2/trace/otlp"
+            headers:
+                "X-SF-Token": "${ACCESS_TOKEN}"
+    ```
 
 # If your change doesn't affect end users or the exported elements of any package,
 # you should instead start your pull request title with [chore] or use the "Skip Changelog" label.