doc: Add documentation for specular* properties of MeshPhysicalMaterial (#23261)

docs/api/en/materials/MeshPhysicalMaterial.html

@@ -159,6 +159,27 @@
 			over sheen tint. Default is *null*.
 		</p>
 
+		<h3>[property:Float specularIntensity]</h3>
+		<p>
+			A float that scales the amount of specular reflection for non-metals only. When set to zero, the model is effectively Lambertian. From *0.0* to *1.0*. Default is *0.0*.
+		</p>
+
+		<h3>[property:Texture specularIntensityMap]</h3>
+		<p>
+			The alpha channel of this texture is multiplied against [page:.specularIntensity], for per-pixel control over specular intensity. Default is *null*.
+		</p>
+
+		<h3>[property:Color specularColor]</h3>
+		<p>
+			A [page:Color] that tints the specular reflection at normal incidence for non-metals only.
+			Default is *0xffffff*, white.
+		</p>
+
+		<h3>[property:Texture specularColorMap]</h3>
+		<p>
+			The RGB channels of this teture are multiplied against [page:.specularColor], for per-pixel control over specular color. Default is *null*.
+		</p>
+
 		<h3>[property:Float transmission]</h3>
 		<p>
 		Degree of transmission (or optical transparency), from *0.0* to *1.0*. Default is *0.0*.<br />

docs/api/zh/materials/MeshPhysicalMaterial.html

@@ -156,6 +156,26 @@
 			over sheen tint. Default is *null*.
 		</p>
 
+		<h3>[property:Float specularIntensity]</h3>
+		<p>
+			用于控制非金属材质高光反射强度的浮点值。漫反射材质对应的值为0。范围从*0.0*到*1.0*。 默认值为*0.0*。
+		</p>
+
+		<h3>[property:Texture specularIntensityMap]</h3>
+		<p>
+			此纹理的alpha通道将与[page:.specularIntensity]相乘，用于逐像素地控制高光强度。默认值为*null*。
+		</p>
+
+		<h3>[property:Color specularColor]</h3>
+		<p>
+			非金属材质在垂直于法线方向观看时的高光反射颜色。默认值为*0xffffff*，白色。
+		</p>
+
+		<h3>[property:Texture specularColorMap]</h3>
+		<p>
+			此纹理的alpha通道将与[page:.specularColor]相乘，用于逐像素地控制高光颜色。默认值为*null*。
+		</p>
+
 		<h3>[property:Float transmission]</h3>
 		<p>
 		Degree of transmission (or optical transparency), from *0.0* to *1.0*. Default is *0.0*.<br />