[Docs] MeshPhongMaterial: Added reflectivity default value and expected range

docs/api/materials/MeshPhongMaterial.html

@@ -182,7 +182,10 @@
 
 
 		<h3>[property:Float reflectivity]</h3>
-		<div>How much the environment map affects the surface; also see [page:.combine].</div>
+		<div>
+			How much the environment map affects the surface; also see [page:.combine]. 
+			The default value is 1 and the valid range is between 0 (no reflections) and 1 (full reflections).
+		</div>
 
 		<h3>[property:Float refractionRatio]</h3>
 		<div>The index of refraction for an environment map using [page:Textures THREE.CubeRefractionMapping]. Default is *0.98*.</div>