changelog for import bug fix

Author: alexcjohnson

CHANGELOG.md

@@ -2,6 +2,10 @@
 All notable changes to `dash` will be documented in this file.
 This project adheres to [Semantic Versioning](https://semver.org/).
 
+## [UNRELEASED]
+### Fixed
+- [#1493](https://github.com/plotly/dash/pull/1493) Fix [#1143](https://github.com/plotly/dash/issues/1143), a bug where having a file with one of several common names (test.py, code.py, org.py, etc) that imports a dash component package would make `import dash` fail with a cryptic error message asking whether you have a file named "dash.py"
+
 ## [1.18.1] - 2020-12-09
 
 ## [1.18.0] - 2020-12-07