Clarify note on ap_discard_request_body(). If we want to change it,

we should do it before .37 - hence its remaining as a showstopper.

Add note on the 304 showstopper (aka PR 9673 in BZ).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95555 13f79535-47bb-0310-9956-ffa450edef68