feat: Improve help documentation

[kjonescertinia]

Is your feature request related to a problem?

Now the hep documentation has been moved to gh-pages we can provide better guidance on how to use the tool. Ideally we would include some screenshots to be better able to guide people.

[lcottercertinia]

I think we should also adopt a theme to aid navigation and search etc.
This one seems to be pretty good https://github.com/just-the-docs/just-the-docs

[lcottercertinia]

#498 Migrates the doc site to docusaurus.
We can now add content much for easily on a much better site going forward