Update render pass tutorial

tutorials/17_render_pass_tutorial.md

@@ -1,6 +1,6 @@
 \page render_pass Render pass
 
-This example shows how to add gaussian mode to the camera
+This example demonstrates the of use the render pass system for adding Gaussian noise post-processing effect to a camera.
 
 ## Compile and run the example
 
@@ -35,6 +35,6 @@ Engine 'optix' is not supported
 
 ## Code
 
-Get the render pass system and check if the render engine has a render pass. Then we just need to create some gaussian noise using the mean and the standard deviation and add this noise to the camera.
+Get the render pass system and create a Gaussian noise render pass. Then we just need to set the noise mean and the standard deviation parameters and apply this render pass to the camera.
 
 \snippet examples/render_pass/Main.cc get render pass system