added IO'18 pong talk an code in featured section
added IO'18 pong talk an code in featured section

Change-Id: I25f61991c0b35f578f61f5e41c63b1366c638a2d

GoogleCloudPlatform/tensorflow-without-a-phd,GoogleCloudPlatform/tensorflow-without-a-phd,GoogleCloudPlatform/tensorflow-without-a-phd,GoogleCloudPlatform/tensorflow-without-a-phd