[docs] can't configure the tooltip for PieChart

[TuPhung369]

tooltip: {
  title: (datum) =>
    `<span style="color: ${COLORS[0]}; font-weight: bold;">${datum.name}</span>`, // Title formatting
  items: [
    {
      channel: "x",
      name: "Role",
      value: "name",
      color: COLORS[0],
    },
    {
      channel: "y",
      name: "Percent",
      value: "value",
      color: COLORS[2],
      valueFormatter: (value) => `${value.toFixed(1)}%`,
    },
  ],
},

But it show

=> the percent show as total of itself and all of indexes before.

can not make the dynamic Colors for tooltip also.