Suggest we implement more gh-actions

[dajmcdon]

Currently only deploying to gh-pages. I suggest:

1. move docs/ to the gh-pages branch. Rebuild the docs automatically on push/merge.
2. Add gh-actions to run the tests and rebuild the package.
3. Add some branch protection to main to prevent push/merge with failing code.

For the automatic rebuilding, we likely should move some of the vignette data (maybe examples too) offline (as suggested in #69). This will generally make R-CMD-Check much faster.

[dajmcdon]

@ryantibs @brookslogan Is it all right with you guys if I go ahead and implement this? There is the potential that 2 will run into cmu-delphi/epidatr#31

[ryantibs]

I'd say go for it---I haven't been following cmu-delphi/epidatr#31, so I think you're in a better position to judge this and how likely it is to run into problem, but sounds like you think it's worth it

Apart from #69, worth implementing tests as in #42. I'm not sure where things stand on the testing front, but we should definitely get around to that ...

[brookslogan]

So in this case would people install_github on main or gh-pages? For install_github to properly allow people to access help functionality, the compiled man entries have to already be there AFAIK (see cmu-delphi/epidatr#15). I don't know how vignettes work, though (if they need to be pre-compiled to be accessible when using install_github or not).

[dajmcdon]

The GitHub pages site is served by the docs/, while the help is in man/. Currently docs/ lives on main, but we would create an orphan branch called gh-pages that contains only docs/. Then remove docs/ from main.

On a push to main, the action will automatically run pkgdown and push the compiled site to the gh-pages branch. That way, you never have to rerun locally, and all the of the site documentation won't be on main. Running install_github("cmu-delphi/epiprocess") would grab main and work as expected.

This is actually a common setup. Running usethis::use_pkgdown_github_pages() sets it up automatically.