Update changelog

Author: holly-hacker

embassy-rp/CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add reset_to_usb_boot for rp235x ([#4705](https://github.com/embassy-rs/embassy/pull/4705))
 - Add fix #4822 in PIO onewire. Change to disable the state machine before setting y register ([#4824](https://github.com/embassy-rs/embassy/pull/4824))
 - Add PIO::Ws2812 color order support
+- Add `dma_push_ping_pong` for PIO to allow sending continuous double-buffered data ([#4784](https://github.com/embassy-rs/embassy/pull/4784))
 
 ## 0.8.0 - 2025-08-26