Update CHANGES.md

Author: lilleyse

CHANGES.md

@@ -22,6 +22,7 @@ Change Log
 * Fixed a crash when using `BingMapsGeocoderService` [#7143](https://github.com/AnalyticalGraphicsInc/cesium/issues/7143)
 * Fixed entity visibility issue related to setting an entity show property and altering or adding entity geometry [#7156](https://github.com/AnalyticalGraphicsInc/cesium/pull/7156)
 * Fixed accuracy of rotation matrix generated by `VelocityOrientationProperty` [#6641](https://github.com/AnalyticalGraphicsInc/cesium/pull/6641)
+* Fixed incorrect rendering of models using the `KHR_materials_common` lights extension. [#7206](https://github.com/AnalyticalGraphicsInc/cesium/pull/7206)
 
 ### 1.50 - 2018-10-01