message: fix Go SDK codegen directory
diff: @@ -28,7 +28,7 @@ These settings apply only when `--tag=package-2019-06 --go` is specified on the
  Please also specify `--go-sdk-folder=<path to the root directory of your azure-sdk-for-go clone>`.
  ``` yaml $(tag) == 'package-2019-06' && $(go)
  -output-folder: $(go-sdk-folder)/services/$(namespace)/mgmt/preview/2019-06-15-preview/$(namespace)
  +output-folder: $(go-sdk-folder)/services/preview/$(namespace)/mgmt/2019-06-15-preview/$(namespace)
  ```
  ### Tag: package-2019-04 and go
  