update changelog

Author: Aearsears

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fixed return value for `Pilot.double_click` and `Pilot.triple_click` https://github.com/Textualize/textual/pull/6035
 - Fixed sizing issue with `Pretty` widget https://github.com/Textualize/textual/pull/6040 https://github.com/Textualize/textual/pull/6041
 - Fixed garbled inline app output when `inline_no_clear=True` https://github.com/Textualize/textual/pull/6080
+- Fixed `Markdown` and `MarkdownViewer` widgets both handling `Markdown.LinkClicked` messages https://github.com/Textualize/textual/pull/6093
 
 ### Added