Moves note about Ubuntu 12.04 LTS with GRE

Change-Id: Iab4fd385ee19aef96be51580f4efa8df44259976
Closes-bug: 1251714
(cherry picked from commit f1aae7a731e519fe43153f0b6457ab104c0008d1)
Merge "Moves note about Ubuntu 12.04 LTS with GRE" into stable/havana