Doc build process to generate man page, help page and docs

[benthayer]

Goes with #144 and #146 It would be nice to only specify each of the command help messages in a single file, which would then be pushed out the the various forms of documentation.

Something to think about here is that we typically develop with git gud in edit mode, which would allows updated code to run on the fly. We want to avoid sacrificing the speed gained by not having a build process.