mod_proxy documentation

[Joshua Slive <jo...@slive.ca>]

I just did a quick update on the mod_proxy documentation.  But since I 
don't really use the proxy myself, and I haven't looked at the code in 
depth, I can only go so far.

We really need one of the proxy gurus to take a look at the 
documentation when they have time so we can eventually get rid of the 
big "out of date" warning at the top.

Thanks.

Joshua.