Add missing entry for #7750 to 15.4.2 changelog

Author: gaearon

CHANGELOG.md

@@ -9,6 +9,7 @@
 
 ### React DOM
 
+* Fixed a decimal point issue on uncontrolled number inputs. ([@nhunzaker](https://github.com/nhunzaker) in [#7750](https://github.com/facebook/react/pull/7750))
 * Fixed rendering of textarea placeholder in IE11. ([@aweary](https://github.com/aweary) in [#8020](https://github.com/facebook/react/pull/8020))
 * Worked around a script engine bug in IE9. ([@eoin](https://github.com/eoin) in [#8018](https://github.com/facebook/react/pull/8018))