Label outside arc (Pie chart) c3.js

Question

I want to show the label data outside the graph area using c3.js. I've not find any help from documentation. Please some one guide me to solve this.

var chart = c3.generate({
    data: {
      columns: data,
      type : 'pie'
    },
    axis: {
      x: {
        label: {
            text: 'data1 ',
            position: 'outer-middle'
        }
      },
      y: {
        label: {
            text: 'data2 ',
            position: 'outer-middle'
        }

      }
    },
    pie: {
      label: {
        show: true
      }
    },  
    onrendered: function() {

    }
});

Thanks in advance