Update App.js

Author: rwieruch

src/App.js

@@ -90,7 +90,7 @@ const Slider = ({
       <SliderHeader>
         <strong ref={currentRef}>{formatFn(initial)}</strong>
         &nbsp;/&nbsp;
-        {max}
+        {{formatFn(max)}}
       </SliderHeader>
       <StyledSlider ref={sliderRef}>
         <StyledThumb