Draft release notes for WESL support (#2027)

Co-authored-by: Alice Cecile <[email protected]>

Author: ElliottjPierce

release-content/0.16/release-notes/17953_Add_support_for_experimental_WESL_shader_source.md

@@ -1,4 +1,16 @@
 <!-- Add support for experimental WESL shader source -->
 <!-- https://github.com/bevyengine/bevy/pull/17953 -->
 
-<!-- TODO -->
+Bevy continues to live life on the edge, the bleeding edge, of graphics technology. Today, Bevy supports [WESL](https://wesl-lang.dev/) shaders!
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+Most Bevy shaders are written in [WGSL](https://www.w3.org/TR/WGSL/), a modern shader language built for simplicity. But while WGSL is pretty simple as far as shader languages go, it also leaves a lot to be desired in terms of features.
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+Currently, Bevy puts extra work into its WGSL shaders to support conditional compiling, importing between files, and other useful features. WESL is a brand new shader language that extends WGSL and aims to bring common language conveniences to the GPU. WESL not only includes conditional compiling and importing between files, but it is also growing to support generics, package managers, and more.
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+It's important to note that WESL is still relatively early in development, and not all of its features are fully functional yet, nor are all its features supported in Bevy (yet). For that reason, WESL support is gated behind a feature, `shader_format_wesl`, which is disabled by default.
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+Despite the additional features, WESL is easy to layer on top of existing WGSL shaders. This is because it is a superset of WGSL, so just like C is valid C++, WGSL is valid WESL. That makes it easy to migrate existing WGSL to WESL, though it's worth mentioning that the Bevy-specific WGSL syntax will need to be ported to its WESL counterparts. The WESL team (who helped write these notes!) is actively listening to feedback, and so is Bevy. If you do choose to use WESL in addition to or in replacement of WGSL, your thoughts, feature requests, and any pain points you encounter can be shared [here](https://github.com/wgsl-tooling-wg/wesl-rs).
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+If you're interested in trying WESL, check out the new [Material - WESL](https://bevyengine.org/examples/shaders/shader-material-wesl/) example. Before using this in a production environment, be sure to check out the original [PR](https://github.com/bevyengine/bevy/pull/17953) for a full list of caviots.
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+WESL is an exciting frontier of shader languages, and as it grows, Bevy intends to grow with it. You can track their progress and plans [here](https://wesl-lang.dev/).