Fix incorrect class in TextChatService overview (#1040)

## Changes

<!-- Please summarize your changes. -->
The method TextChatService:SendAsync() does not exist, it should be
TextChannel:SendAsync()
<!-- Please link to any applicable information (forum posts, bug
reports, etc.). -->

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---------

Author: dgxo

content/en-us/chat/in-experience-text-chat.md

@@ -127,7 +127,7 @@ Though both systems share the same basic chat functionalities, TextChatService i
       <td>Send a chat message</td>
       <td>`Class.Players:Chat()`</td>
       <td>`Class.TextChannel:SendAsync()`</td>
-      <td>The `Class.TextChatService:SendAsync()` method supports more advanced chat features, such as rich text formatting and message priority. It also includes built-in filtering to help prevent inappropriate messages from being sent.</td>
+      <td>The `Class.TextChannel:SendAsync()|SendAsync()` method supports more advanced chat features, such as rich text formatting and message priority. It also includes built-in filtering to help prevent inappropriate messages from being sent.</td>
     </tr>
     <tr>
       <td>Implement messaging callbacks</td>