feedback in http://httpd.apache.org/docs/2.4/mod/mod_ssl.html#comment_5818

This added paragraph about optional and optional_no_ca isn't helpful.

At the TLS layer, the challenge for otpional and required are no different.

Move the caution about _no_ca up into where the option is defined
and reword.




git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1761215 13f79535-47bb-0310-9956-ffa450edef68