Description for yaml provisioning is wrong

[atimmerm93]

In the src/README.md is a description for the yaml based provisioning of AWS IoT SiteWise as a datasource. Unfortunately the type is wrong. It is not datasource but grafana-iot-sitewise-datasource was quite tricky for me to figure that out as it is my first time using grafana. So the files should be changed from ->

apiVersion: 1

datasources:

• name: IoT Sitewise
  type: datasource
  jsonData:
  authType: credentials
  defaultRegion: us-east-1

to ->

apiVersion: 1

datasources:

• name: IoT Sitewise
  type: grafana-iot-sitewise-datasource
  jsonData:
  authType: credentials
  defaultRegion: us-east-1