rename files from *.asc to *.adoc

In a world ravaged by software that determines file type by the last
part of the file's name, *.asc is somewhat troublesome given file
managers that think these are PGP keys.  Also GitHub won't render
AsciiDoc without one of a few extensions, at least *.adoc is somewhat
clearer and not as obnoxiously long as *.asciidoc
patches: New blood spats to replace the TNT placeholders