[schreck61]

What

GOVERNANCE.md now names Chris Miller (csm0513) as the backup maintainer:

• the intro says who the backup maintainer is;
• the roles table gains a Backup maintainer row;
• a new Continuity section describes how the project keeps going if the maintainer dies, is incapacitated or can no longer maintain it.
  • First week: the backup maintainer answers and closes issues, merges pull requests whose required checks pass, and makes releases.
  • Access: they already hold write access to the repository, co-ownership of the crate on crates.io and the maintainer's GitHub successor designation.
  • No credentials: no passwords or keys change hands, because GitHub Actions builds, signs and publishes every release.

Why

This covers the access_continuity criterion of the OpenSSF Best Practices silver badge: the project must be able to handle issues, accept changes and release within a week of losing any one person. The roles table also makes clear who holds each role, as roles_responsibilities asks.

Testing

All three kinds of access were checked before this change:

• csm0513 is a collaborator with the write role, with no pending invitations;
• csm0513 is listed under the maintainer's GitHub successor settings, not pending;
• csm0513 is an owner of the crate on crates.io.

Documentation only; no code changes.