Hook sample object generation into Github actions

[jernst]

Currently Makefile needs to be run manually.
Is there a way of doing this periodically?

See also #9.

[andypiper]

I think we can possibly just add this as a make step into the GH Action that does the pages deployment; however, we currently also store the generated content in the repository, so it may be better to have an action that runs that make step and commits the files back to git.

[andypiper]

Alternatively we could make this a commit hook I guess.