Add a Kits top-level section and a PocketBeagle Grove Kit entry
Links to the critical information are at https://beagleboard.org/Kits/Grove.
Be sure to notice:
- https://github.com/beagleboard/cloud9-examples/blob/master/PocketBeagle/Grove/Kit.md
- https://github.com/beagleboard/cloud9-examples/blob/master/PocketBeagle/Grove/Kit-setup.md (this is to customize an image, rather than use an image that is already customized)
- The custom images: https://debian.beagle.cc/images/grove/