Sync documentation now carries blog/releases/<version>.md into the
pnpm.io publish commit. pnpm/pnpm.io writes the page from the changelog
section the release PR curated, read at the signed release commit, so
the release page and the GitHub release body share one source and patch
releases get pages too.
Release pages are added without clearing the directory, which keeps the
hand-written pages for earlier releases.
Gate documentation publication on creation of a generated commit.
An unchanged import exits the commit step successfully, but must also skip
credential lookup and pushing. Emit changed=true after a successful commit
and use it as the condition for the push step.