Call to undefined method Laravel\Spark\Spark::referToTeamAs()

I am trying to change how Spark refers to teams. I am using the instructions here: https://spark.laravel.com/docs/2.0/teams

This is my current code in the SparkServiceProvider.php file:

public function booted()
    {
        Spark::useStripe()->noCardUpFront()->teamTrialDays(14);

        Spark::chargeTeamsPerMember();

        Spark::freePlan()
            ->features([
                'First', 'Second', 'Third'
            ]);

        Spark::teamPlan('Basic', 'provider-id-1')
            ->price(29)
            ->features([
                'First', 'Second', 'Third'
            ]); 

        Spark::teamPlan('Basic Pro', 'provider-id-2')
            ->price(49)
            ->features([
                'First', 'Second', 'Third'
            ]); 
    }

    public function register()
    {
        Spark::referToTeamAs('website');
    }

I can't quite figure out what I am doing wrong. Is the register method syntax incorrect?