[STUMP] Porting stumpwm.nongnu.org to stumpwm.github.io

Hi All,

I've ported most relevant content to stumpwm.github.io.  Its my plan to
have stumpwm.nongnu.org point to stumpwm.github.io through a CNAME
change (github supports this).  Right now, the git repo hosts the html,
as well as a set of org documents that export to the html.

The styling is all done from css, and its the same style that I'm using
for the manual that we iterated on a few months ago.  

Let me know what you think, if there's no negative push-back I'm going
to update the CNAME record in the next week or two.

Cheers,

    Dave