Reworded the Timeout documentation about mod_cgi[d]

After a chat with Yann and Eric on dev@, we agreed to
simplify the description.

PR: 60404 
Follow up of: http://svn.apache.org/r1780907



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1780918 13f79535-47bb-0310-9956-ffa450edef68