fix broken link in config-agents doc
fix broken link in config-agents doc

Testing Ia7c282b7331f0b624bb3324f27dfec223cf414f7 found a broken link
in the config-agents doc. This patch updates the link.

Change-Id: I5cc146b58f3eebade9ff746a1d1fed018cd9e074

mahak/neutron,noironetworks/neutron,mahak/neutron,eayunstack/neutron,openstack/neutron,huntxu/neutron,noironetworks/neutron,eayunstack/neutron,huntxu/neutron,openstack/neutron,mahak/neutron,openstack/neutron