[racket] Apache improvements

I've recently enabled gzip compression on most of the
*.racket-lang.org pages, and so far there are no problems.

Another thing that I was considering is adding expiration, but I'm not
sure if there's a best way to do this, and what value to use.  It
looks like a good feature to have to speed up searches on
docs.racket-lang.org.

Does anyone know whether it's worth it?  I've seen some texts that
say that this should be done to "enable caching", but IIUC that only
saves a HEAD ping for the file so maybe the benefits are not important
enough?  Also, it's not clear to me how to do it (it's an apache
setup) and what's a value that would be fine.

I'll be happy if anyone can help with that.  (Please reply directly.)

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!