Generated actions.lock headers link to https://gh.io/actions-lockfile, which currently redirects logged-out readers to a private early-access repository and returns 404. Point the header at the public Workflow dependency lockfiles documentation instead, and update the two existing serialized-output expectations.

Fixes #184.

This intentionally changes the header comment written on the next save of an existing lockfile. Dependency pins and workflow behavior are unchanged.

Validation with Go 1.25.8:

• Live link checks: old URL → private repository / HTTP 404; new documentation → HTTP 200.
• Both corrected-header expectations fail against the original emitter.
• go test -race -count=1 ./... passes.
• make fmt-check and make vet pass; the CLI builds and runs --version.
• Independent Standards and Spec reviews: no findings.

Ruby/live-API integration catalog scenarios and other OS platforms were not run.