update CHANGELOG.md

Author: mpenkov

CHANGELOG.md

@@ -1,6 +1,13 @@
 Changes
 =======
 
+## 4.0.1, 2021-04-01
+
+Bugfix release to address issues with Wheels on Windows:
+
+- https://github.com/RaRe-Technologies/gensim/issues/3095
+- https://github.com/RaRe-Technologies/gensim/issues/3097
+
 ## 4.0.0, 2021-03-24
 
 **⚠️ Gensim 4.0 contains breaking API changes! See the [Migration guide](https://github.com/RaRe-Technologies/gensim/wiki/Migrating-from-Gensim-3.x-to-4) to update your existing Gensim 3.x code and models.**