Adding an example curl request when creating a user

[carl-alberto]

Happy to add more example in the REST API documentation to give more context on its usage :)

[TimothyBJacobs]

Thanks for the PR @carl-alberto! Unfortunately, the reference is generated automatically. So any changes made to those files won't persist.

We'd like to be able to do something like this in the future, #91. But I'm going to go ahead and close this for now, since we can't really action it atm.