post_action docs

[Rob Mueller]

To reply to myself...

> 2. I want to pass a header returned by the upstream server to the 
> post_action handler for logging purposes, but I'm not sure how to do that. 
> I must be missing something obvious here.
>
>      fastcgi_param  PARAM_EXTRA_1   ...some upstream header...;

I found this previous post:

http://article.gmane.org/gmane.comp.web.nginx.english/1305

Which seems to fix issue 2 nicely. Now if only I could fix the first issue.

Rob