code: function(options) {
          var userOptions = options;
          var series = userOptions.series;
          if (!series) {
              return userOptions;
          }
          series.forEach(function(value, index) {
              if (Object.keys(userOptions.yScales).length < 2 && Object.keys(userOptions.yScales).indexOf(value.yScale) === -1 && value.yScale === 'secondary') {
                  userOptions.yScales[value.yScale] = {
                      scaling: 'linear',
                      minValue: 'auto',
                      maxValue: 'auto',
                      displayOnAxis: 'right'
                  };
              }
          });
          return userOptions;
      }
docs: adds secondary scale if necessary