message: update Developer.md
  fixed a typo
diff: @@ -101,7 +101,7 @@ docker pull reldocker.tibco.com/flogo/state-service:latest
  Rename the state service image:
  ```sh
  -docker tag reldocker.tibco.com/flogo/state-service:latest flogo/sate-service:latest
  +docker tag reldocker.tibco.com/flogo/state-service:latest flogo/state-service:latest
  ```
  Pull the flow service image
  