Move all AsciiDoc materials into the subfolder `asciidoc/`

This promotes the development of asciidoctor, which already appears much easier to manage. None-the-less, the AsciiDoc stuff must remain online until complete feature parity is achieved.
Merge pull request #11 from gregturn/move-asciidoc

Move all AsciiDoc materials into the subfolder `asciidoc/`