Function run 

pub fn run(cfg: Config)

a wrapper function to do the boilerplate of a basic, statically defined blog:

• pull the in and out directories out of the args, including a little help message
• read the blog from the input and write it to the output

usage is simple; build your Config and pass it in.

the cli is, admittedly, a little more complex:

• -h/--help/help: print some help text
• run <in> <out>: run the blog generation once, writing it to <out>
• serve <in>: serve the blog directly off disk