updated readme

Author: hannared

README.md

@@ -55,6 +55,7 @@ function CityPicker() {
 | `containerStyle`         | `StyleProp<ViewStyle>`    | Style of the picker.                                                                                                                                                                                                                                                        |
 | `selectedIndicatorStyle` | `StyleProp<ViewStyle>`    | Style of overlaying selected-indicator in the middle of the picker.                                                                                                                                                                                                         |
 | `rotationFunction`       | `(x: number) => number `  | Function to determine the x rotation of items based on their current distance to the center (which is x). Default is ![rotation equation](https://latex.codecogs.com/gif.latex?%5Csmall%20f%28x%29%20%3D%201%20-%20%5Cleft%20%28%201%5Cover2%20%5Cright%20%29%20%5E%7Bx%7D) |
+| `scaleFunction`       | `(x: number) => number `  | Function to determine the scale of items based on their current distance to the center (which is x). Default is "1.0" |
 | `opacityFunction`        | `(x: number) => number`   | Function to determine the opacity of items based on their current distance to the center (which is x). Default is ![opacity equation](https://latex.codecogs.com/gif.latex?%5Csmall%20f%28x%29%20%3D%20%5Cleft%20%28%201%5Cover3%20%5Cright%20%29%20%5E%7Bx%7D)             |
 | `decelerationRate`       | "normal", "fast", number  | How quickly the underlying scroll view decelerates after the user lifts their finger. See the [ScrollView docs](https://facebook.github.io/react-native/docs/scrollview.html#decelerationrate). Default is "fast".                                                          |
 | `containerProps`         | `ViewProps`               | Props that are applied to the container which wraps the `FlatList` and the selected indicator.                                                                                                                                                                              |