Update changelog

Author: holly-hacker

embassy-rp/CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - add `wait_for_alarm` and `alarm_scheduled` methods to rtc module ([#4216](https://github.com/embassy-rs/embassy/pull/4216))
 - rp235x: use msplim for stack guard instead of MPU
 - Add reset_to_usb_boot for rp235x ([#4705](https://github.com/embassy-rs/embassy/pull/4705))
+- 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