Fix small typo in Material.dispose docs (#28750)

* fix: small typo on docs/Material/dispose

* get back "of"

docs/api/en/materials/Material.html

@@ -407,7 +407,7 @@
 			method whenever this instance is no longer used in your app.
 		</p>
 		<p>
-			Material textures must be be disposed of by the dispose() method of
+			Material textures must be disposed of by the dispose() method of
 			[page:Texture Texture].
 		</p>