A seasoned programmer's take on Nim's docs

[cblake]

Thanks. I did similar in `cligen` for multi-commands to get a [default 
pre-commandList blurb from the top of a module doc 
comment](https://github.com/c-blake/cligen/blob/master/cligen/macUt.nim#L128). 
Even short blurbs can add lots of context to ident names & types...I'm not sure 
if the impatient devs @jtv mentioned were looking at The Index.