PR#50174: don't offer 120ms as a "typical" TCP keepalive frequency. Initial...

PR#50174: don't offer 120ms as a "typical" TCP keepalive frequency.  Initial keepalive timers can be
as high as 2 hours (windows/linux/solars defaults via google).  

Drive home the idea that users need
to figure out their OS and Firewall timers and make the former smaller than th elatter.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1031062 13f79535-47bb-0310-9956-ffa450edef68