updated example to consider circleci_token

Author: Amark19

src/examples/set_browserstack_config.yml

@@ -1,5 +1,5 @@
 description: |
-  This example demonstrates how to set BrowserStack config in Job Scope.
+  This example demonstrates how to set BrowserStack config in Job Scope. (CIRCLECI_TOKEN needs to be set in CircleCI project environment variables)
 
 usage:
   version: 2.1