Remove old post_processing example (#8376)

# Objective

- The old post processing example doesn't use the actual post processing
features of bevy. It also has some issues with resizing. It's also
causing some confusion for people because accessing the prepass textures
from it is not easy.
- There's already a render to texture example
- At this point, it's mostly obsolete since the post_process_pass
example is more complete and shows the recommended way to do post
processing in bevy. It's a bit more complicated, but it's well
documented and I'm working on simplifying it even more

## Solution

- Remove the old post_processing example
- Rename post_process_pass to post_processing


## Reviewer Notes
The diff is really noisy because of the rename, but I didn't change any
code in the example.

---------

Co-authored-by: James Liu <contact@jamessliu.com>

Cargo.toml

@@ -1415,16 +1415,6 @@ name = "post_processing"
 path = "examples/shader/post_processing.rs"
 
 [package.metadata.example.post_processing]
-name = "Post Processing - Render To Texture"
-description = "A custom post processing effect, using two cameras, with one reusing the render texture of the first one"
-category = "Shaders"
-wasm = true
-
-[[example]]
-name = "post_process_pass"
-path = "examples/shader/post_process_pass.rs"
-
-[package.metadata.example.post_process_pass]
 name = "Post Processing - Custom Render Pass"
 description = "A custom post processing effect, using a custom render pass that runs after the main pass"
 category = "Shaders"

examples/README.md

@@ -280,8 +280,7 @@ Example | Description
 [Material - GLSL](../examples/shader/shader_material_glsl.rs) | A shader that uses the GLSL shading language
 [Material - Screenspace Texture](../examples/shader/shader_material_screenspace_texture.rs) | A shader that samples a texture with view-independent UV coordinates
 [Material Prepass](../examples/shader/shader_prepass.rs) | A shader that uses the various textures generated by the prepass
-[Post Processing - Custom Render Pass](../examples/shader/post_process_pass.rs) | A custom post processing effect, using a custom render pass that runs after the main pass
-[Post Processing - Render To Texture](../examples/shader/post_processing.rs) | A custom post processing effect, using two cameras, with one reusing the render texture of the first one
+[Post Processing - Custom Render Pass](../examples/shader/post_processing.rs) | A custom post processing effect, using a custom render pass that runs after the main pass
 [Shader Defs](../examples/shader/shader_defs.rs) | A shader that uses "shaders defs" (a bevy tool to selectively toggle parts of a shader)
 [Texture Binding Array (Bindless Textures)](../examples/shader/texture_binding_array.rs) | A shader that shows how to bind and sample multiple textures as a binding array (a.k.a. bindless textures).