doc: security release announcement safety check

Github Actions could have an outage and we should abort the publishing
of the PR if they are.

Author: mcollina

doc/guides/security-release-process.md

@@ -35,6 +35,8 @@ information described.
 
 ## Announcement (one week in advance of the planned release)
 
+* [ ] Verify that GitHub Actions are working as normal: <https://www.githubstatus.com/>.
+
 * [ ] Check that all vulnerabilities are ready for release integration:
   * PRs against all affected release lines or cherry-pick clean
   * Approved