title: Chart JS add max value to legend
body: <p>I'm new in Chart JS and I'm trying to add the maximum values for each dataset inside the legend. I've tried using <code>legendCallback</code> :</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;canvas id="lineChart"&gt;&lt;/canvas&gt;
  </code></pre>
  
  <p>Javascript:</p>
  
  <pre><code>var ctx = document.getElementById("lineChart");
      var lineChart = new Chart(ctx, {
          type: 'line',
          data: {
              labels: ['1','2','3','4','5','6','7','8','9','10'],
              datasets: [{
                  label: "Max",
                  backgroundColor: "rgba(235, 70, 70, 0.31)",
                  borderColor: "rgba(231, 25, 25, 0.7)",
                  pointBorderColor: "rgba(231, 25, 25, 0.7)",
                  pointBackgroundColor: "rgba(231, 25, 25, 0.7)",
                  pointHoverBackgroundColor: "#fff",
                  pointHoverBorderColor: "rgba(220,220,220,1)",
                  pointBorderWidth: 1,
                  data: [31, 74, 6, 39, 20, 85, 7, 80, 35, 70]
              }, {
                  label: "Avg",
                  backgroundColor: "rgba(255, 255, 111, 0.3)",
                  borderColor: "rgba(255, 255, 50, 0.70)",
                  pointBorderColor: "rgba(255, 255, 50, 0.70)",
                  pointBackgroundColor: "rgba(255, 255, 50, 0.70)",
                  pointHoverBackgroundColor: "#fff",
                  pointHoverBorderColor: "rgba(151,187,205,1)",
                  pointBorderWidth: 1,
                  data: [82, 23, 66, 9, 99, 4, 2, 25, 67, 20]
              },
              {
                  label: "Min",
                  backgroundColor: "rgba(90, 189, 90, 0.3)",
                  borderColor: "rgba(50, 173, 50, 0.70)",
                  pointBorderColor: "rgba(50, 173, 50, 0.70)",
                  pointBackgroundColor: "rgba(50, 173, 50, 0.70)",
                  pointHoverBackgroundColor: "#fff",
                  pointHoverBorderColor: "rgba(151,187,205,1)",
                  pointBorderWidth: 1,
                  data: [30, 46, 60, 29, 79, 54, 23, 25, 47, 10]
              }]
          },
          options: {
              legend: {
                  display: true,
                  position: 'bottom'
              },
              legendCallback: function(chart) {
                  return 'a';
              },
              scales: {
                  xAxes: [{
                      gridLines: {
                          color: "rgba(0, 0, 0, 0)",
                      }
                  }]
              }
          }
      });
  </code></pre>
  
  <p>but the displayed legend didn't changed. I've searched for some answers and I also tried using: <code>lineChart.generateLegend();</code> but still no result.</p>
  
  <p>It is possible to add the maximum value for each dataset inside legend?
  Thanks in advance!</p>