Add GitHub workflow for automatic plugin releases

[marcusquinn]

No description provided.

[superdav42]

I just committed a build step to #23. Should be as easy as npm run build to create the archive and now it's under 10mb. But I'm interested it making it part of this git workflow. The workflow just needs updated to run npm run build. It will makepot, minify css and js and other things that this does not do now. When does this github workflow trigger to actually create the release?

[marcusquinn]

With some luck, this should work.

Readme files updated with explainers.

In short, tagging should trigger the Github build action.