Update CHANGELOG.md

Co-authored-by: Emmanuelle Gouillart <emma@plot.ly>

Author: nicolaskruchten

CHANGELOG.md

@@ -6,7 +6,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Updated
 
-- `plotly.express.imshow` now uses data frame index names and values to populate axis parameters by default ([#2539](https://github.com/plotly/plotly.py/pull/2539))
+- `plotly.express.imshow` now uses data frame index and columns names and values to populate axis parameters by default ([#2539](https://github.com/plotly/plotly.py/pull/2539))
 
 ## [4.8.2] - unreleased