Fix syntax errors in Standalone code example

[reywood]

TODO:

• Make sure all of new logic is covered by tests and passes linting
• Update CHANGELOG.md with your change

[apollo-cla]

@reywood: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Apollo Contributor License Agreement here: https://contribute.apollographql.com/

[wdibi]

Suggested change

	operationName: {}, //optional
	operationName: '', //optional

I think operationName should be an empty String not an empty Object.