Update CHANGES

Author: lilleyse

CHANGES.md

@@ -28,6 +28,7 @@ Change Log
 * Fixed a crash for 3D Tiles that have zero volume. [#7945](https://github.com/AnalyticalGraphicsInc/cesium/pull/7945)
 * Fixed a bug where dynamic polylines did not use the given arcType. [#8191](https://github.com/AnalyticalGraphicsInc/cesium/issues/8191)
 * Fixed a bug where GlobeSurfaceTile would not render the tile until all layers completed loading causing globe to appear to hang. [#7974](https://github.com/AnalyticalGraphicsInc/cesium/issues/7974)
+* Fixed alpha equation for `BlendingState.ALPHA_BLEND` and `BlendingState.ADDITIVE_BLEND`. [#8202](https://github.com/AnalyticalGraphicsInc/cesium/pull/8202)
 
 ### 1.61 - 2019-09-03