Update drv_charts.c

Add a chart title

src/driver/drv_charts.c

@@ -504,7 +504,8 @@ void Chart_Display(http_request_t *request, chart_t *s) {
  poststr(request, " beginAtZero: false");
  poststr(request, " }");
  }
- poststr(request, " }");
+ poststr(request, " }, "); // EHorvat: Needs an additional "," to display chart title in next line
+ poststr(request, " plugins: { title: { display: true, color:'#099', text: '2 Stunden Trendkurve' } } "); // EHorvat: new line, display a chart titel
  poststr(request, " }");
  poststr(request, "});");
  poststr(request, "Chart.defaults.color = '#099'; "); // Issue #1375, add a default color to improve readability (applies to: dataset names, axis ticks, color for axes title, (use color: '#099')