README.md: drop mention of ct_integration_test (#1240)
README.md: drop mention of ct_integration_test (#1240)

Fixes #1233
Martin2112/trillian,Martin2112/trillian,daviddrysdale/trillian,gdbelvin/trillian,google/trillian,RJPercival/trillian,gdbelvin/trillian,AlCutter/trillian,gdbelvin/trillian,RJPercival/trillian,daviddrysdale/trillian,AlCutter/trillian,daviddrysdale/trillian,Martin2112/trillian,google/trillian