Minor repository updates

[mattstratton]

There are a few github features that we can take advantage of and might want to explore:

• Update GH pages (currently hosted at http://devopsdays.github.io/devopsdays-cli/; the current page is both out of date and also not very helpful. We should either figure out a way to update it (maybe using mkdocs or hugo with a good docs template) or just get rid of it
• Social sharing image for the repo - GH supports Upload an image to customize your repository’s social media preview.. this could be nice :)