It looks like the history behind this is that the Guidelines were updated before that package was added,
but the package was not ever created.
See redhat-rpm-config#51,
where the templates part was apparently never merged.

I suppose the solution is to simply drop the reference to the non-existing package?
For now, these templates are only available in the Packaging Guidelines.

The following pull request fixes this issue and some other problems with the SourceURL page: #1216

Commit fcf4c9d fixes this issue