Update CHANGELOG entry

.chloggen/exp-es-omit-attributes-prefix.yaml

@@ -7,15 +7,21 @@ change_type: enhancement
 component: elasticsearchexporter
 
 # A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
-note: Add `mapping.omit_attributes_prefix` configuration option
+note: Add `mapping.mode: raw` configuration option
 
 # Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
 issues: [26647]
 
 # (Optional) One or more lines of additional information to render under the primary note.
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-subtext:
+subtext: |
+  Setting `mapping.mode: raw` in the Elasticsearch exporter's configuration
+  will result logs and traces being indexed into Elasticsearch with their
+  attribute fields directly at the root level of the document instead inside an
+  `Attributes` object. Similarly, this setting will also result in traces being
+  indexed into Elasticsearch with their event fields directly at the root level
+  of the document instead of inside an `Events` object.
 
 # 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.