Update CHANGES.md to show issue #36470 is fixed in 2.69.0 release. (#36477)

Author: jiangzzhu

CHANGES.md

@@ -99,6 +99,7 @@
 * PulsarIO has now changed support status from incomplete to experimental. Both read and writes should now minimally
   function (un-partitioned topics, without schema support, timestamp ordered messages for read) (Java)
   ([#36141](https://github.com/apache/beam/issues/36141)).
+* Fixed Spanner Change Stream reading stuck issue due to watermark of partition moving backwards ([#36470](https://github.com/apache/beam/issues/36470)).
 
 ## Known Issues
 
@@ -153,7 +154,11 @@
 * (Python) Fixed Java YAML provider fails on Windows ([#35617](https://github.com/apache/beam/issues/35617)).
 * Fixed BigQueryIO creating temporary datasets in wrong project when temp_dataset is specified with a different project than the pipeline project. For some jobs, temporary datasets will now be created in the correct project (Python) ([#35813](https://github.com/apache/beam/issues/35813)).
 * (Go) Fix duplicates due to reads after blind writes to Bag State ([#35869](https://github.com/apache/beam/issues/35869)).
-  * Earlier Go SDK versions can avoid the issue by not reading in the same call after a blind write.
+* Earlier Go SDK versions can avoid the issue by not reading in the same call after a blind write.
+
+## Known Issues
+
+* ([#36470](https://github.com/apache/beam/issues/36470)). Spanner Change Stream reading stuck issue due to watermark of partition moving backwards. This issue exists in 2.67.0 and 2.68.0. To mitigate the issue, either use old version 2.66.0 or go to 2.69.0.
 
 # [2.67.0] - 2025-08-12
 
@@ -201,6 +206,7 @@
 ## Known Issues
 
 * ([#35666](https://github.com/apache/beam/issues/35666)). YAML Flatten incorrectly drops fields when input PCollections' schema are different. This issue exists for all versions since 2.52.0.
+* ([#36470](https://github.com/apache/beam/issues/36470)). Spanner Change Stream reading stuck issue due to watermark of partition moving backwards. This issue exists in 2.67.0 and 2.68.0. To mitigate the issue, either use old version 2.66.0 or go to 2.69.0.
 
 # [2.66.0] - 2025-07-01