Give more accurate instructions on how to increase HARD_SERVER_LIMIT

for the case where MaxClients > HARD_SERVER_LIMIT.

Reviewed by:	Dean Gaudet (hey it's a doc change!)
Submitted by:	Marc Slemko


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3@78693 13f79535-47bb-0310-9956-ffa450edef68