update references, culling dead links and the dead SSLv2 protocol.

Pending: update of the actual content.
The text reads like it's ten years old, like certificate chaining
is the hot new shit. It's not, people still get it wrong. We should
address that. Among other things..


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1328523 13f79535-47bb-0310-9956-ffa450edef68