The images are linked relative to page now. This prevents the mkdocs
warnings and also let these images render itself nicely inside the
editor or github interface.

This way of referencing also helps for future if the docs get deployed
to a path instead of a top-level domain

- Add page last edited info on each page
- Update header - site title, repo name & icon
- Disable custom fonts, use system-fonts
- Add copyright info in footer
- Update navigation structure and behaviour
- Add source code view and edit buttons
- Refractor documentation