Render Kroxylicious Javadoc (or redirect to Javadoc.io) on the website with Jekyll

[gracegrimwood]

Relates to #44 and kroxylicious/kroxylicious#238

I think it would simplify things if we rendered the Javadoc ourselves on the website (because we could then apply site styles and link back to the website from the Javadoc pages for easier navigation) but at the very least we should link to the Javadoc from the site. Jekyll doesn't have a plugin for Javadoc, but as Maven is capable of spitting out static site files from Javadoc and Jekyll is capable of handling static files, we can just tell Jekyll to serve them as-is.

Related to #44 because if we were to render it on the website I imagine it would be a very similar process to what we'd need to do with the AsciiDoc, although without the need for any new Jekyll plugins.

[k-wall]

I think linking to Javadoc.io is good enough.