Use better doc link for onLongPress (#573)

* Fixed doc link for long press

* Hard-code date for code link

README.md

@@ -127,7 +127,7 @@ e.g.
 - **`onPressAvatar`** _(Function(`user`))_ - Callback when a message avatar is tapped
 - **`renderAvatarOnTop`** _(Bool)_ - Render the message avatar at the top of consecutive messages, rather than the bottom; default is `false`
 - **`renderBubble`** _(Function)_ - Custom message bubble
-- **`onLongPress`** _(Function(`context`, `message`))_ - Callback when a message bubble is long-pressed; default is to show an ActionSheet with "Copy Text" (see [example using `showActionSheetWithOptions()`](https://github.com/FaridSafi/react-native-gifted-chat/blob/master/example/CustomActions.js))
+- **`onLongPress`** _(Function(`context`, `message`))_ - Callback when a message bubble is long-pressed; default is to show an ActionSheet with "Copy Text" (see [example using `showActionSheetWithOptions()`](https://github.com/FaridSafi/react-native-gifted-chat/blob/master@%7B2017-09-25%7D/src/Bubble.js#L96-L119))
 - **`renderMessage`** _(Function)_ - Custom message container
 - **`renderMessageText`** _(Function)_ - Custom message text
 - **`renderMessageImage`** _(Function)_ - Custom message image