Remove additional newline in Introduction to shaders

This newline creates an unwanted paragraph.

tutorials/shaders/introduction_to_shaders.rst

@@ -133,7 +133,6 @@ Fragment processor
 ^^^^^^^^^^^^^^^^^^
 
 The ``fragment()`` processing function is used to set up the Godot material
-
 parameters per pixel. This code runs on every visible pixel the object or
 primitive draws. It is only available in ``spatial`` and ``canvas_item`` shaders.