A little clarification of the command line which is to be typed. People

seem to like to have an example of EXACTLY what they are supposed to
type.
Also, added a "subtitle" for the File Descriptor Limits page, to reflect
some of the material that I just added to it.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95702 13f79535-47bb-0310-9956-ffa450edef68