message: fix short code snippet for 'how to: add price line'
diff: @@ -20,8 +20,8 @@ A price line can be added to a chart by using the
  ```js
  const myPriceLine = {
  price: 1234,
  - color: BAR_UP_COLOR,
  - lineWidth: lineWidth,
  + color: '#3179F5',
  + lineWidth: 2,
  lineStyle: 2, // LineStyle.Dashed
  axisLabelVisible: true,
  title: 'my label',
  