Separate catalog from package

[jonthegeek]

The catalog is updated daily, but we only update data-raw when we think about it. We should separate the data into a separate data package with more frequent updates, so we can keep the "functions for using Project Gutenberg" package history cleanly separated from the "catalog data" history.

We could update the data package daily on GitHub via GitHub actions. We could then set up a schedule or rules for how often to update that other package on CRAN (perhaps once X titles have changed or something along those lines). We could also include instructions in this package for downloading the dev version of the data package.

This project will have multiple moving parts, and we'll need to talk to someone about the policies of ropensci for splitting off a dependency like that (I suspect we might have to put it through the full review process).

There's no rush on this, I just wanted to log my thoughts.