GitHub Pages action should allow for maintenance

[rowanc1]

Right now our GitHub action directly installs node packages and builds. We should recommend a path that abstract this and allows us to make changes for users. This would also allow us to, for example, add additional features for PDF builds etc under options, which are going to take multiple passes to improve but maintain the same action interface.

An example of doing that is here, which also has some basic code for PDF support.