Improve workflow to reviewing monitored specs

[tidoust]

Via #1477 (comment)

Creating a pull request directly means that it's less convenient to make changes as the issue/PR mechanism that we have in place would create merge conflicts with the pull request. A better workflow could perhaps be:

1. Report all specs to monitor in an issue with checkboxes.
2. Review specs to monitor, check those that look correct as is
3. Handle manual updates in separate issues/PRs
4. Tell bot to create a PR that bumps the review date for all checked specs