docs: update release-doc-sync header comment to reflect actual @v1 / @v1.X convention

[TMHSDigital]

The header comment in .github/actions/release-doc-sync/action.yml (lines 30-32 approximately) currently says:

tool repos MUST consume this action via @v1.0 (or a SHA), never @main. The meta-repo's tag pipeline maintains the v1.0 tag pointing at the latest 1.x.y.

This advice is stale. The v1.0 tag was never created. DTD#42 fixed the runtime default of the meta-repo-ref input from v1.0 to v1, but the header comment was not updated in the same change to keep the diff scoped.

Actual current convention

• Most consumers pin via @v1 (floating major, auto-maintained on every release by release.yml)
• Strict consumers pin via @v1.X (floating minor, e.g., @v1.9, also auto-maintained)
• @v1.0 does not exist and never did

Fix

Update the action header comment to reflect actual current convention. Replace the @v1.0 reference with @v1 (floating major) and note @v1.X as the strict-pin alternative. Optionally adjust the cross-reference to DTD#14 if any wording in the comment now implies the v1.0 tag is in flight.

Documentation only. No runtime behavior change. Surfaced during DTD#42 work.

Scope

Single edit to action.yml header comment plus VERSION bump. No PR-body required beyond a brief note.

Estimate

5 to 10 minutes.