Add error restructure to changelog

Author: faern

CHANGELOG.md

@@ -22,6 +22,9 @@ Line wrap the file at 100 chars.                                              Th
 
 
 ## [Unreleased]
+### Changed
+- Change the public API of `ApplyTcpOptionsError`. So this is a breaking change. This stops
+  exposing the internal details of the type which allows future changes to not be breaking.
 
 
 ## [0.4.0] - 2024-01-02