Revert "(docs) Stop the "provider" parameter from overriding the #doc method"

This reverts commit b7da88c7a3bf51351e9074a7ee5ee495a70ba282. Since we aren't
turning the external generator into a long-lived part of the Puppet code, we're
erring on the side of less change to core.
Account for the loss of commit b7da88c

If we aren't stopping it from appending this junk, we can de-append it in the collector.