Adds information about change of default.

Change-Id: I9041345bbffefe6059d5ff151ebff07b6e26321a
Related: blueprint add-ssl-internal-network

This patch introduces a global keep alive timeout value for services
that leverage httpd + wsgi to handle http/https requests. The default
value is one minute.

Change-Id: Icf7cb0baf86b428a60a7e9bbed642999711865cd
Partially-Implements: blueprint add-ssl-internal-network