docs(void): state that only the wheel is byte-reproducible

The canonical sdist is built from the tag, but a second build of the same
commit differs in tar and gzip timestamps, so its digest is recorded from the
published asset, not from a rebuild. Correct the comments and docs that said
"reproducible sdist". No behaviour change.

docs/RELEASE_PROCESS.md

@@ -558,7 +558,7 @@ approved each time: the workflow has no schedule and no manual trigger.
 3. **Runner check.** podman, python3.11, uv 0.12/0.13, openssl, git and curl
    must be on the runner, or the job names what is missing and stops.
 4. **Release.** `build-release.sh release` builds the canonical sdist from the
-   tag (reproducibly), builds every template in the pinned Void glibc container
+   tag, builds every template in the pinned Void glibc container
    without the key, signs the repository in a second container with no network,
    and installs `voculinux` from that repository in a clean image without the key.
    A local dry run is `just void-release vX.Y.Z` with `XBPS_SIGNING_KEY_FILE`