Update Material.js
Update Material.js

Changed wording material filter documentation
likangning93/cesium,YonatanKra/cesium,CesiumGS/cesium,likangning93/cesium,progsung/cesium,CesiumGS/cesium,AnalyticalGraphicsInc/cesium,CesiumGS/cesium,CesiumGS/cesium,YonatanKra/cesium,likangning93/cesium,YonatanKra/cesium,likangning93/cesium,YonatanKra/cesium,progsung/cesium,likangning93/cesium,CesiumGS/cesium,AnalyticalGraphicsInc/cesium