Remove what are shaders page and description from your_first_shader/

tutorials/shading/your_first_shader/index.rst

@@ -7,9 +7,6 @@ with the basics. This tutorial will not cover advanced topics and it is not
 comprehensive. For a comprehensive and detailed overview of shaders in Godot see the
 :ref:`Shading Reference Page <toc-shading-reference>`.
 
-"What are shaders" gives you a high-level overview of what shaders are and how they fit
-into the rendering pipeline.
-
 The "your first shader" tutorials walk you through the process of writing a shader
 step-by-step.
 
@@ -20,7 +17,6 @@ For a more general introduction into shaders and the OpenGL Shading Language, us
    :maxdepth: 1
    :name: toc-your-first-shader
 
-   what_are_shaders
    your_first_2d_shader
    your_first_3d_shader
    your_second_3d_shader

tutorials/shading/your_first_shader/your_first_2d_shader.rst

@@ -9,7 +9,7 @@ Introduction
 Shaders are special programs that execute on the GPU and are used for rendering
 graphics. All modern rendering is done with shaders. For a more detailed
 description of what shaders are please see :ref:`What are shaders
-<doc_what_are_shaders>`.
+<doc_introduction_to_shaders>`.
 
 This tutorial will focus on the practical aspects of writing shader programs by
 walking you through the process of writing a shader with both vertex and