Add label for first dataset in progress-bar example (#5625)
Add label for first dataset in progress-bar example (#5625)

While the second dataset already has a label ("My Second dataset") the first dataset showed "undefined" as a label. Added a label to the first dataset object.
chartjs/Chart.js,chartjs/Chart.js,simonbrunel/Chart.js,jtcorbett/Chart.js,touletan/Chart.js,chartjs/Chart.js,nnnick/Chart.js,chartjs/Chart.js,touletan/Chart.js,jtcorbett/Chart.js,touletan/Chart.js,simonbrunel/Chart.js,touletan/Chart.js