Add warning that if instance groups exists in 2.X upgrade

[norman-abramovitz]

The genesis manifest may fail if the environment has instance groups. Instance group names changed in cf 2.X.

Task 191536 | 22:26:14 | Error: Required property 'release' was not specified in object ({"name"=>"cloud_controller_worker", "pdiff --git a/cf/snw-nabramovitz-lab.yml b/cf/snw-nabramovitz-lab.yml
index 38d2379..aa09537 100644
--- a/cf/snw-nabramovitz-lab.yml
+++ b/cf/snw-nabramovitz-lab.yml