release notes 0.9.0 - oversight

Updated release notes for version 0.9.0 to reflect changes in unsafe surface reduction, migration to rustix, and performance improvements.

docs/src/release-notes/0.9.0.md

@@ -33,7 +33,7 @@ We are excited to announce the release of **Rust Coreutils 0.9.0** - a release f
   - A sustained, project-wide push to shrink the `unsafe` surface: dozens of `unsafe` removals across utilities, tests, fuzz targets and `uucore` (`get_groups`, `make_fifo`, `build.rs`, and more)
   - Migration from `nix`/`libc` to `rustix` across `id`, `tr`, `timeout`, `sort`, `wc`, `tail`, `cp`, `who`, `factor`, and core process/IO paths
 
-- **Performance: zero-copy I/O**
+- **Performance**
   - `splice()`/`tee()`/`pipe()` fast paths landed across `cat`, `wc`, `head`, `tail`, `yes`, `cp`, `tee`, and `unexpand` (e.g. `unexpand` +7.5%, faster `cp` from a pipe on Linux, `tee` via raw syscalls, `yes` using the `tee` syscall)
   - Consolidated in a reworked `uucore::pipes` / `buf_copy`