Update changelog with more details

Author: pawankartik-elastic

docs/changelog/127636.yaml

@@ -7,7 +7,11 @@ issues:
 breaking:
   title: Disallow mixed quoted/unquoted patterns in FROM
   area: ES|QL
-  details: Please describe the details of this change for the release notes. You can
-    use asciidoc.
-  impact: Please describe the impact of this change to users
+  details: "Previously, the ES|QL grammar allowed users to individually quote constituent strings in index patterns\
+    \ such as \"remote_cluster\":\"index_name\". This would allow users to write complex malformed index patterns\
+    \ that often slip through grammar and the subsequent validation. This could result in runtime errors\
+    \ that can be misleading. This change simplifies the grammar to early reject such malformed index patterns\
+    \ at the parsing stage, allowing users to write simpler queries and see more relevant and meaningful\
+    \ errors."
+  impact: "Users can write queries with simpler index patterns and see more meaningful and relevant errors."
   notable: false