Migrate contributing guidelines to the contributing docs (#1246)

CONTRIBUTING.md

@@ -2,108 +2,4 @@
 
 Thanks for your interest in contributing to the Godot demo projects!
 
-## Demo submission criteria
-
-Please follow these guidelines for submitting new demos or improving existing demos:
-
-- The demo must work with the latest Godot version of the branch you're submitting to.
-
-- The demo must follow all of the Godot style guides:
-  - [Project organization](https://docs.godotengine.org/en/stable/tutorials/best_practices/project_organization.html)
-  - [GDScript style guide](https://docs.godotengine.org/en/stable/tutorials/scripting/gdscript/gdscript_styleguide.html)
-    - In GDScript, type hints should be used whenever possible to improve runtime performance
-    and ease code maintenance. The **Debug > GDScript > Warnings > Untyped Declaration**
-    project setting is set to **Warn** on most existing demos to enforce this.
-    This setting should also be configured to **Warn** on new demos.
-  - [C# style guide](https://docs.godotengine.org/en/stable/tutorials/scripting/c_sharp/c_sharp_style_guide.html)
-  - [Shaders style guide](https://docs.godotengine.org/en/stable/tutorials/shaders/shaders_style_guide.html)
-
-- The demo should not be overcomplicated. Simplicity is usually preferred.
-
-- The submitted files must be freely redistributable and modifiable,
-  including for commercial use. This applies to art assets as well.
-  - In practice, this means the following licenses are accepted for art assets:
-    - CC0 1.0 (or similar public domain dedications)
-    - CC BY 3.0/4.0
-    - CC BY-SA 3.0/4.0
-  - Licenses such as "Royalty-free" (without clarification), CC BY-NC or
-    CC BY-ND are **not** accepted.
-
-- To allow demos to be cloned quickly, file sizes should be kept reasonable for
-  all files submitted. Try to keep the demo project files's download size below
-  20 MB, unless there is a good reason to have a larger demo (e.g. if
-  high-quality textures are *required* to show off an effect).
-  - You can check this by creating a ZIP file containing the project files,
-    then removing `.godot/` within the ZIP file.
-  - For 3D demos, consider relying on Godot's procedural generation abilities
-    (such as [NoiseTexture2D](https://docs.godotengine.org/en/stable/classes/class_noisetexture2d.html))
-    to decrease file size.
-
-### Submission criteria for new demos
-
-If you are submitting a new demo:
-
-- Make sure it includes a `README.md` file similar to the other demos.
-
-- Make sure a short description (1-3 lines) is set in the Project Settings.
-
-- Make sure the project has a `icon.webp` in lossless WebP[^1] format that is
-  128×128 pixels, with its path defined in the Project Settings. This allows the
-  icon to remain crisp on hiDPI displays.
-
-- Make sure the project includes a `screenshots/` folder containing a screenshot in
-  lossless WebP[^1] format similar to the other demos. It's recommended to stick to
-  only 1 screenshot, but you may add multiple screenshots if required. The
-  screenshot should be in 1280×720 resolution, without visible window borders.
-  - The `screenshots/` folder must contain an empty `.gdignore` file to prevent
-    Godot from importing screenshots as resources.
-
-- Make sure the demo has keyboard and controller input support (plus mouse if
-  relevant). Explicit touch input support is a bonus, but not required.
-  - For keyboard events, WASD configurations must use *physical* key locations
-    in the Input Map to allow them to work out of the box on non-QWERTY keyboard
-    layouts.
-
-#### Visual considerations
-
-- Unless the project requires a different stretch mode and aspect, use the
-  `canvas_items` stretch mode and `expand` stretch aspect in the Project
-  Settings. Configure anchors for Control nodes correctly, so that
-  [multiple resolutions](https://docs.godotengine.org/en/stable/tutorials/rendering/multiple_resolutions.html)
-  and aspect ratios are supported.
-
-- Demos that don't update their visual output often (such as UI demos) must have
-  **Low Processor Mode** enabled in the Project Settings. This must be left
-  disabled in demos where constant redrawing is expected (such as most "game"
-  demos).
-
-- For greater performance and compatibility, use the **Compatibility** rendering
-  method in 2D demos that don't require advanced graphics functionality.
-  - In 3D demos or 2D demos that require advanced graphics functionality, use
-    the **Forward+** rendering method (**Mobile** is automatically used on
-    mobile platforms in this case).
-
-- In 3D projects, set **Rendering > Textures > Default Filters > Anisotropic Filtering Level**
-   to **16×** in the Project Settings. Make sure all materials use the relevant
-   anisotropic sampler mode (**Nearest Mipmaps Anisotropic** or **Linear Mipmaps Anisotropic**).
-- In 3D projects, set **Rendering > Anti Aliasing > Quality > MSAA 3D** to **4×**.
-  - In projects that use demanding graphics features such as SDFGI, set
-  **Rendering > Anti Aliasing > Quality > Screen Space AA** to **FXAA** instead
-  as this is faster.
-- Use graphics options that perform reasonably well on low-end to mid-range
-  hardware. Demanding graphics options should not be enabled by default, unless
-  they're the entire point of the demo.
-
-#### If you are submitting a copy of a demo translated to C#
-
-- Please ensure that there is a good reason to have this demo translated. We
-  don't want to have multiple copies of every single project, as this makes
-  maintenance more difficult.
-
-- Please ensure that the code mirrors the original as closely as possible.
-
-- In the `project.godot` file and in the `README.md`, include "with C#" in
-  the title, and also include a link to the original in the `README.md`.
-
-[^1]: You can use [Squoosh](https://squoosh.app/) to convert images to WebP.
-Make sure to enable the Lossless option, as it's not the default.
+The guidelines for contributing to godot-demo-projects are documented in the [Godot contributing docs](https://contributing.godotengine.org/en/latest/other/demos.html).