[docs] pie > showZero

<!DOCTYPE html>
<html>
 
<head>
  <meta charset="utf-8">
  <title>ZingSoft Demo</title>
 
  <script nonce="undefined" src="https://cdn.zingchart.com/zingchart.min.js"></script>
  <style></style>
</head>
 
<body>
  <div id='myChart'></div>
  <script>
    ZC.LICENSE = ["569d52cefae586f634c54f86dc99e6a9", "b55b025e438fa8a98e32482b5f768ff5"];
    let chartConfig = {
      type: 'pie',
      plot: {
        showZero: true
      },
      series: [{
          values: [0]
        },
        {
          values: [55]
        },
        {
          values: [130]
        },
        {
          values: [28]
        },
        {
          values: [15]
        }
      ]
    };
 
    zingchart.render({
      id: 'myChart',
      data: chartConfig,
      height: 400,
      width: '100%'
    });
  </script>
</body>
 
</html>

<!DOCTYPE html>
<html>
 
<head>
  <meta charset="utf-8">
  <title>ZingSoft Demo</title>
 
  <script src="https://cdn.zingchart.com/zingchart.min.js"></script>
</head>
 
<body>
  <div id='myChart'></div>
</body>
 
</html>

let chartConfig = {
  type: 'pie',
  plot: {
    showZero: true
  },
  series: [{
      values: [0]
    },
    {
      values: [55]
    },
    {
      values: [130]
    },
    {
      values: [28]
    },
    {
      values: [15]
    }
  ]
};
 
zingchart.render({
  id: 'myChart',
  data: chartConfig,
  height: 400,
  width: '100%'
});