amend text in accordance to further review on 43650:

- re-word section, to do a better job of explaining that DHCP and L3 agents need Linux network namespace support if overlappping IP addresses are in use on the same host.

Change-Id: I867c7af8659044791c8b54cc3ebfaec73c9ae52f
Merge "amend text in accordance to further review on 43650:"