Add a note about the assets_path method

guide/src/tutorials/draw/drawing-images.md

@@ -73,7 +73,7 @@ struct Model {
 # }
 ```
 
-Next, we'll need to create a GPU texture to initialize the struct with. We can accomplish this by loading a texture from an image file after we create the window in our `model` function.
+Next, we'll need to create a GPU texture to initialize the struct with. We can accomplish this by loading a texture from an image file after we create the window in our `model` function. We will let nannou find the assets directory for us using the app's [`assets_path()`](https://docs.rs/nannou/0.14.1/nannou/app/struct.App.html#method.assets_path) method, so we only need to spell out the image path from the root of that directory.
 
 ```rust,no_run
 # #![allow(unreachable_code, unused_variables, dead_code)]