## Why
The Rust release workflow accepts alpha versions with a second numeric suffix,
such as `1.2.3-alpha.4.1`, but the R2 publisher rejects them as invalid.
## What changed
- Allow up to two numeric suffix components for alpha versions in
`publish_r2_release.py`.
- Document that its version pattern must remain aligned with release tag
validation in `rust-release.yml`.
GitOrigin-RevId: 8df68ce4f4d3e652367f7394a642827f21979d70
3d519bf63a