Added DevTools 4.0.4 CHANGELOG entry

Author: Brian Vaughn

packages/react-devtools/CHANGELOG.md

@@ -12,6 +12,10 @@
 * Standalone DevTools properly serves backend script over localhost:8097
 </details>
 
+## 4.0.4 (August 18, 2019)
+#### Bug fixes
+* Bugfox for potential error if a min-duration commit filter is applied after selecting a fiber in the Profiler UI.
+
 ## 4.0.3 (August 17, 2019)
 #### Bug fixes
 * ES6 `Map` and `Set`, typed arrays, and other unnserializable types (e.g. Immutable JS) can now be inspected.