title: How do you hide the title of a chart tooltip?
body: <p>I'm using chart js to show grouped bar chart and try to hide the title of the tooltip</p>
  
  <p>Code to generate bar </p>
  
  <pre><code>var ctx = document.getElementById("myChart").getContext("2d");
  
  var data = {
      labels: ["Chocolate", "Vanilla", "Strawberry"],
      datasets: [
          {
              label: "Blue",
              backgroundColor: "blue",
              data: [3,7,4]
          },
          {
              label: "Red",
              backgroundColor: "red",
              data: [4,3,5]
          },
          {
              label: "Green",
              backgroundColor: "green",
              data: [7,2,6]
          }
      ]
  };
  
  var myBarChart = new Chart(ctx, {
      type: 'bar',
      data: data,
      options: {
          barValueSpacing: 20,
          scales: {
              yAxes: [{
                  ticks: {
                      min: 0,
                  }
              }]
          }
      }
  });
  </code></pre>
  
  <p>In the tooltip it showing the labels Chocolate,Vanilla,Strawberry and i have tried to hide the label with following</p>
  
  <p>by setting the titlefontsize to 0 but it doesnt work</p>
  
  <pre><code>tooltipTitleFontSize: 0
  </code></pre>
  
  <p>and i have tried with the tooltip callbacks it disables the label blue,red,green but i wont need that</p>
  
  <pre><code> tooltips: {
          callbacks: {
             label: function(tooltipItem) {
                    return tooltipItem.yLabel;
             }
          }
      }
  </code></pre>
  
  <p>Help me thanks in  advance</p>