Fix onEndReached props on FlatList and SectionList

Author: maarekj

src/components/flatList.rei

@@ -53,7 +53,7 @@ let make:
  ~initialNumToRender: int=?,
  ~initialScrollIndex: int=?,
  ~numColumns: 'int=?,
- ~onEndReached: {. "distanceFromEnd": float}=?,
+ ~onEndReached: {. "distanceFromEnd": float} => unit=?,
  ~onEndReachedThreshold: float=?,
  ~onRefresh: unit => unit=?,
  ~onViewableItemsChanged: {

src/components/sectionList.re

@@ -147,7 +147,7 @@ let make:
  ~sectionSeparatorComponent: separatorComponent('item)=?,
  ~extraData: 'extraData=?,
  ~initialNumToRender: int=?,
- ~onEndReached: {. "distanceFromEnd": float}=?,
+ ~onEndReached: {. "distanceFromEnd": float} => unit=?,
  ~onEndReachedThreshold: float=?,
  ~onViewableItemsChanged: {
  .

src/components/sectionList.rei

@@ -69,7 +69,7 @@ let make:
  ~sectionSeparatorComponent: separatorComponent('item)=?,
  ~extraData: 'extraData=?,
  ~initialNumToRender: int=?,
- ~onEndReached: {. "distanceFromEnd": float}=?,
+ ~onEndReached: {. "distanceFromEnd": float} => unit=?,
  ~onEndReachedThreshold: float=?,
  ~onViewableItemsChanged: {
  .