Doc: Adjust CHANGELOG.md

Author: coastalwhite

riscv-rt/CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Use inline assembly instead of pre-compiled blobs
 - Removed bors in favor of GitHub Merge Queue
 - `start_trap_rust` is now marked as `unsafe`
+- Implement `r0` as inline assembly
 
 ## [v0.11.0] - 2023-01-18