docs: update upgrade helper guide

Author: vishalnarkhede

docusaurus/docs/reactnative/basics/upgrade_helper.mdx

@@ -18,6 +18,14 @@ yarn remove @react-native-community/cameraroll
 yarn add @stream-io/react-native-cameraroll
 ```
 
+## Prop or Context Changes
+
+Following values in [`ImageGalleryContext`](https://getstream.io/chat/docs/sdk/reactnative/v5/contexts/image-gallery-context/#value) have been renamed
+  - `image` -> `selectedMessage`
+  - `setImage` -> `setSelectedMessage`
+  - `images` -> `messages`
+  - `setImages` -> `setMessages`
+
 ## Enable Offline Support
 
 Offline Support is a major opt-in feature introduced in v5 of SDK.