feat: added new docs

docusaurus/docs/Flutter/stream_chat_flutter/message_widget.mdx

@@ -45,4 +45,52 @@ class ChannelPage extends StatelessWidget {
 ### Building A Custom Attachment
 
 When a custom attachment type (location, audio, etc.) is sent, the MessageWidget also needs to know
-how to build it.
+how to build it. For this purpose, we can use the `customAttachmentBuilders` parameter.
+
+As an example, if a message has a attachment type 'location', we do:
+
+```dart
+MessageWidget(
+    //...
+    customAttachmentBuilders: {
+        'location': (context, message, attachments) {
+            var attachmentWidget = Image.network(
+              _buildMapAttachment(
+                attachments[0].extraData['latitude'],
+                attachments[0].extraData['longitude'],
+              ),
+            );
+
+        return wrapAttachmentWidget(context, attachmentWidget, null, true, BorderRadius.circular(8.0));
+    }
+  },
+)
+```
+
+You can also override the builder for existing attachment types like `image` and `video`.
+
+### Show User Avatar For Messages
+
+You can decide to show, hide, or remove user avatars of the sender of the message. To do this, set
+the `showUserAvatar` property like this:
+
+```dart
+MessageWidget(
+    //...
+    showUserAvatar = DisplayWidget.show,
+)
+```
+
+### Reverse the message
+
+In most cases, `MessageWidget` needs to be a different orientation depending upon if the sender is the
+user or someone else.
+
+For this, we use the `reverse` parameter to change the orientation of the message:
+
+```dart
+MessageWidget(
+    //...
+    reverse = true,
+)
+```