changelog [skipci]

Author: willmcgugan

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Fixed markup escaping edge cases https://github.com/Textualize/textual/pull/5697
 - Fixed incorrect auto height in Collapsible https://github.com/Textualize/textual/pull/5703
+- Fixed issue with keymaps and single-letter keys https://github.com/Textualize/textual/pull/5726
 
 ### Changed