Move documentation to Github pages

[willwh]

As per https://jenkins.io/blog/2019/10/21/plugin-docs-on-github/ time to move Docs over to Github as a final push for Hacktoberfest, thankfully, this is fairly simple.

We may need to move some of the images that are currently linked in the Readme.md in the event @vipinsthename decides he wants to delete this original ;)