Need more doc about modifying a response - especially since Harmon doesn't work

[steph643]

Harmon doesn't work with the latest version of http-proxy (see No9/harmon#46).
For this reason, and also because one might not want to use Harmon, it would be great to have some more explanation about modifying a response.

[andrebautista]

@steph643 Have you had any success with this in the past couple days? I've been banging my head against the keyboard trying to use harmon and just now realized that it's not supported. I found this snippet awhile back nodejitsu/node-http-proxy#796

[steph643]

@andrebautista: I use http-proxy-response-rewrite.