DOC: Update changelog

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * A `#version_history` URI fragment which can be used to directly open the modal
   with the full version history of the first entity on the page.
+* `BUILD_MODULE_SHOW_ID_IN_LABEL` build variable with which the showing of
+  entity ids together with their names is enabled (disabled by default).
 
 ### Changed (for changes in existing functionality)