bump benchmark-bbs
bump benchmark-bbs

[finishes #118223207]

Submodule src/github.com/cloudfoundry-incubator/benchmark-bbs a3e6241..a88e9f2:
  > Document how to run against sql in bosh-lite

Signed-off-by: Connor Braa <e624947c8d30070ca3f5f65daa9bdf76de21947b@pivotal.io>

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release