move buildTimeDist chart to examples

too esoteric for the front page, converting it to an example
of querying laminar db directly and using gnuplot should provide
more value to those needing deeper insights into job behaviour.

src/resources/index.html

@@ -71,7 +71,6 @@
     <div><canvas id="chartBpj"></canvas></div>
     <div><canvas id="chartTpj"></canvas></div>
     <div><canvas id="chartBuildTimeChanges"></canvas></div>
-    <div><canvas id="chartBuildTimeDist"></canvas></div>
    </div>
   </section>
  </div></template>

src/resources/js/app.js

@@ -350,20 +350,6 @@ const Home = function() {
             }
           }
         });
-        var chtBuildTimeDist = new Chart(document.getElementById("chartBuildTimeDist"), {
-          type: 'line',
-          data: {
-            labels: ['<30s','30s-1m','1m-5m','5m-10m','10m-20m','20m-40m','40m-60m','>60m'],
-            datasets: [{
-              label: 'Number jobs with average build time in range',
-              data: msg.buildTimeDist,
-              backgroundColor: "#7483af",
-            }]
-          },
-          options: {
-            title: { display: true, text: 'Build time distribution' }
-          }
-        });
       },
       job_queued: function(data) {
         state.jobsQueued.splice(0, 0, data);