Update CHANGES.md to mention breakign change around ProcessContext (#36530)

Author: stankiewicz

CHANGES.md

@@ -121,6 +121,7 @@
 * (Go) Coder construction on SDK side is more faithful to the specs from runners without stripping length-prefix. This may break streaming pipeline update as the underlying coder could be changed ([#36387](https://github.com/apache/beam/issues/36387)).
 * Minimum Go version for Beam Go updated to 1.25.2 ([#36461](https://github.com/apache/beam/issues/36461)).
 * (Java) DoFn OutputReceiver now requires implementing a builder method as part of extended metadata support for elements ([#34902](https://github.com/apache/beam/issues/34902)).
+* (Java) Removed ProcessContext outputWindowedValue introduced in 2.68 that allowed setting offset and record Id. Use OutputReceiver's builder to set those field ([#36523]https://github.com/apache/beam/pull/36523).
 
 ## Deprecations