LUDOC-147 lnet: Describe routes config in Manual

LUDOC-147 lnet: Describe routes config in Manual

Describe how to dynamically configure LNET routes using the two new
scripts which were added: luster_routes_config and
lustre_routes_conversion.
Sections 15.5 was added in the Lustre Manual.

LU-2950 tracks the change which landed to provide the
above functionality.

Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Change-Id: I3974286bce9d726abd12a5deb568740bca4544aa
Reviewed-on: http://review.whamcloud.com/6538
Tested-by: Hudson
Reviewed-by: Richard Henwood <richard.henwood@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Linda Bebernes <linda.bebernes@intel.com>