Add intrinsics for dot4{I,U}8Packed to changelog

Author: robamler

CHANGELOG.md

@@ -56,7 +56,7 @@ Bottom level categories:
 
 Naga now infers the correct binding layout when a resource appears only in an assignment to `_`. By @andyleiserson in [#7540](https://github.com/gfx-rs/wgpu/pull/7540).
 
-- Add polyfills for `dot4U8Packed` and `dot4I8Packed` for all backends. By @robamler in [#7494](https://github.com/gfx-rs/wgpu/pull/7494).
+- Implement `dot4U8Packed` and `dot4I8Packed` for all backends, using specialized intrinsics on SPIR-V and HSLS if available, and polyfills everywhere else. By @robamler in [#7494](https://github.com/gfx-rs/wgpu/pull/7494) and [#7574](https://github.com/gfx-rs/wgpu/pull/7574).
 - Add polyfilled `pack4x{I,U}8Clamped` built-ins to all backends and WGSL frontend. By @ErichDonGubler in [#7546](https://github.com/gfx-rs/wgpu/pull/7546).
 - Allow textureLoad's sample index arg to be unsigned. By @jimblandy in [#7625](https://github.com/gfx-rs/wgpu/pull/7625).
 - Properly convert arguments to atomic operations. By @jimblandy in [#7573](https://github.com/gfx-rs/wgpu/pull/7573).