Add doc

src/Materials/Node/nodeMaterial.ts

@@ -733,6 +733,7 @@ export class NodeMaterial extends PushMaterial {
      * @param reusable If the post process can be reused on the same frame. (default: false)
      * @param textureType Type of textures used when performing the post process. (default: 0)
      * @param textureFormat Format of textures used when performing the post process. (default: TEXTUREFORMAT_RGBA)
+     * @returns the post process created
      */
     public createPostProcess(
         camera: Nullable<Camera>, options: number | PostProcessOptions = 1, samplingMode: number = Constants.TEXTURE_NEAREST_SAMPLINGMODE, engine?: Engine, reusable?: boolean,