Fix GCE service account scope instructions

Probably the typo comes from copy/pasting this part of the readme from the grafana stackdriver datasource docs.

Author: blackjid

README.md

@@ -119,7 +119,7 @@ If Grafana is running on a Google Compute Engine (GCE) virtual machine, it is po
 
 1. First of all, you need to create a Service Account that can be used by the GCE virtual machine. See detailed instructions on how to do that [here](https://cloud.google.com/compute/docs/access/create-enable-service-accounts-for-instances#createanewserviceaccount).
 2. Make sure the GCE virtual machine instance is being run as the service account that you just created. See instructions [here](https://cloud.google.com/compute/docs/access/create-enable-service-accounts-for-instances#using).
-3. Allow access to the `Stackdriver Monitoring API` scope. See instructions [here](changeserviceaccountandscopes).
+3. Allow access to the `BigQuery API` scope. See instructions [here](changeserviceaccountandscopes).
 
 Read more about creating and enabling service accounts for GCE VM instances [here](https://cloud.google.com/compute/docs/access/create-enable-service-accounts-for-instances).