message: StorageDataLake: fix invalid readme input file
  The error introduced is an ARM requirement.
diff: @@ -38,7 +38,7 @@ These settings apply only when `--tag=package-2018-06-preview` is specified on t
  ``` yaml $(tag) == 'package-2018-06-preview'
  input-file:
  -- Microsoft.StorageDataLake/preview/2018-06-17/DataLakeStorage.json
  +- preview/2018-06-17/DataLakeStorage.json
  ```
  ---
  