Set up a Github Action to build this repository with Maven and jenkins.webtide.net.

@olamy can you setup a jenkins job that does a full build?

I think you can probably just setup env and run 'jetty-website.sh stage' and that ought to do it all.

bonus points it if is triggered on changes in the documentation subdir of the jetty project since I think that will be the primary source of errors that we want to suss out early.