Document that Buildifier also checks format issues (#536)
Document that Buildifier also checks format issues (#536)

Part of https://github.com/bazelbuild/continuous-integration/issues/506
bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration