DocumentDB connection string

Azure application settings (for azure function) has a option for a DocumentDB connection string

Anyone have any idea how this should be populated/formatted?

i currently use:

var documentDbEndpointUri = new Uri(ConfigurationManager.AppSettings["DocumentDbEndpointUri"]);
            var documentDbAuthKey = ConfigurationManager.AppSettings["DocumentDbAuthKey"];
            return new DocumentClient(documentDbEndpointUri, documentDbAuthKey);

Although I'd like to switch to a single value connection string.