[3384028589] Upstream Reporter: Steven Presti
Upstream issue status: Closed
Upstream description:

1. 1. Bump distro version

• [x] Rename `config/distro/vD_exp` to `config/distro/vD` and update `package` statements. Update imports.
• [x] Drop `-experimental` from `init()` in `config/config.go`.
• [x] Drop `-experimental` from examples in `docs/`.
• [x] Copy `config/distro/vD` to `config/distro/vD+1_exp`.
• [x] Update `package` statements in `config/distro/vD+1_exp`. Bump its base dependency to `base/vB+1_exp`.
• [x] Import `config/vD+1_exp` in `config/config.go` and add `distro` `C+1-experimental` to `init()`.

1. 1. Update docs

• [x] Update `internal/doc/main.go` to add the new stable spec and reference the new experimental spec in `generate()`.
• [x] Run `generate` to regenerate spec docs.
• [x] Update `docs/specs.md`.
• [x] Update `docs/upgrading-*.md` for the new spec version. Copy the relevant section from Ignition's `doc/migrating-configs.md`, convert the configs to Butane configs, convert field names to snake case, and update wording as needed. Add subsections for any new Butane-specific features.
• [x] Note the stabilization in `docs/release-notes.md`, following the format of previous stabilizations. Drop the `-exp` version suffix from any notes for the upcoming release.