correct spelling in comment

src/Mesh/babylon.meshBuilder.ts

@@ -822,7 +822,7 @@
 		};
 
         /**
-         * Creates an extruded polygon mesh, with depth in th Y direction. 
+         * Creates an extruded polygon mesh, with depth in the Y direction. 
 		*/
 
 		public static ExtrudePolygon(name: string, options: {shape: Vector3[], holes?: Vector3[][], depth?: number, updatable?: boolean, sideOrientation?: number, frontUVs?: Vector4, backUVs?: Vector4}, scene: Scene): Mesh {