docs: updated attachment custom property guide

Author: vishalnarkhede

docusaurus/docs/reactnative/guides/attachment_customizations.mdx

@@ -335,26 +335,51 @@ export default function App() {
 }
 ```
 
-## Memoization handler for custom attachment properties
+## Handling Custom Properties On Attachment
 
-When we add a custom property to the attachment format, and the data is changed around that property, the component is not rerendered by default. This should be fixed by passing a custom handler to the prop [`isAttachmentEqual`](../core-components/channel.mdx#isattachmentequal) to [Channel](../core-components/channel.mdx) component.
-The logic should be implemented by the user by itself and must be similar to an equality check function we pass to a [React.memo](https://reactjs.org/docs/react-api.html#reactmemo) as a second argument.
+Default UI components and context providers from the SDK are memoized for performance purpose, and will not trigger re-renders upon updates to
+custom properties on attachment. Please refer to [memoization guide](../customization/custom_components.mdx#equality) for reference.
 
-Eg: Suppose we add a `customField` property to the attachment object. We want to use the value of this field from the message object and have an update in the UI every time the property's value changes. We can do this by implementing a memoization handler for this field as below:
+Eg: Suppose we add a `customField` property to the attachment object and use it the UI in custom `Card` component.
+
+```tsx
+<Channel
+  Card={attachment => {
+    return (
+      <View>
+        <Text>{attachment.customField}</Text>
+      </View>
+    );
+  }}
+/>
+```
+
+In this example, if you try to update `customField` on particular attachment from backend (or anywhere), you will not see it updated on UI until you refresh the chat.
+
+The reason being, the default memoization logic only checks for fixed set of properties on attachment, and doesn't check for custom properties.
+
+This can be solved by providing a function which checks for changes in custom properties which you may have been defined on attachment.
 
 ```tsx
 import { Channel } from 'stream-chat-react-native';
 
-const isAttachmentEqualHandler = (prevAttachment,  nextAttachment) => {
+const isAttachmentEqualHandler = (prevAttachment, nextAttachment) => {
   const attachmentEqual = prevAttachment.customField === nextAttachment.customField;
   if (!attachmentEqual) return false;
   return true;
 };
 
 <Channel
-  ...
+  channel={channel}
   isAttachmentEqual={isAttachmentEqualHandler}
+  Card={attachment => {
+    return (
+      <View>
+        <Text>{attachment.customField}</Text>
+      </View>
+    );
+  }}
 >
   {/* The underlying components */}
-</Channel>
+</Channel>;
 ```