correct the versioning note: a version is a branch on the kernel repo, not a tag

SKILL.md

@@ -154,8 +154,24 @@ reports it, except the package's `supports_*` will already have promised it to t
 Upload `build/` plus `README.md` (with `tags: [kernel]`), and keep the sources in the repo so it stays
 reproducible. Then, in increasing order of surprise:
 
-1. **Tag a version.** `get_kernel` refuses an unpinned repo: "A kernel version or revision must be
-   specified". Create a `v<major>.<minor>.<patch>` tag, load with `version=<major>`.
+1. **A version is a *branch*, not a tag.** `get_kernel` refuses an unpinned repo ("A kernel version
+   or revision must be specified"), but `version=N` resolves by listing refs on the **kernel** repo
+   (`repo_type="kernel"`) and matching *branches* named `v<int>` -- see `kernels/_versions.py`,
+   `_get_available_versions`. Tags are never read, and the model repo is never consulted. This is
+   what `build-and-upload` writes, so **every upload republishes what existing consumers resolve**;
+   there is no immutable pin, and freezing one means a new branch (`v2`), not a tag.
+
+   Two consequences that cost time:
+
+   - **`build-and-upload` writes only `v1`, leaving the kernel repo's `main` stale** -- and `main` is
+     what the Hub page renders, so the backend badge (e.g. the Metal logo) silently disappears or
+     goes out of date. After uploading, fast-forward it:
+     `git clone https://huggingface.co/kernels/<ns>/<name> && git push -f origin origin/v1:refs/heads/main`
+   - **A `v<major>.<minor>.<patch>` tag on the *model* repo is a human marker** of which source
+     commit produced a build -- useful, but load-bearing for nobody. Keep it with plain git
+     (`git tag -d v1.0.0 && git tag v1.0.0 HEAD && git push -f <hub-remote> refs/tags/v1.0.0`), not
+     `HfApi.create_tag`: the API writes only on the Hub and never touches your clone, so the tag your
+     editor shows keeps pointing at an old commit while the API cheerfully reports it correct.
 2. **Trust.** `get_kernel` loads unattended only from a publisher the Hub marks as a trusted kernel
    publisher (e.g. `kernels-community`). A personal repo needs `trust_remote_code=True`, i.e. the
    caller opting into running downloaded code — so a library should not pass it silently.