Update changelog (Azure#41061)

Author: xiangyan99

sdk/search/azure-search-documents/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## 11.6.0b12 (Unreleased)
+## 11.6.0b12 (2025-05-14)
 
 ### Features Added
 
@@ -38,10 +38,6 @@
     - `azure.search.documents.indexes.models.RankingOrder`
     - `azure.search.documents.indexes.models.SearchIndexPermissionFilterOption`
 
-### Breaking Changes
-
-### Bugs Fixed
-
 ### Other Changes
 
 - Updated the API version to "2025-05-01-preview"