Update TextChatService API reference to call attention to new TextCha… (#904)

…nnel-related feature

## Changes

<!-- Please summarize your changes. -->

<!-- Please link to any applicable information (forum posts, bug
reports, etc.). -->

## Checks

By submitting your pull request for review, you agree to the following:

- [x] This contribution was created in whole or in part by me, and I
have the right to submit it under the terms of this repository's open
source licenses.
- [x] I understand and agree that this contribution and a record of it
are public, maintained indefinitely, and may be redistributed under the
terms of this repository's open source licenses.
- [x] To the best of my knowledge, all proposed changes are accurate.

Author: teresayangg

content/en-us/reference/engine/classes/TextChatService.yaml

@@ -218,6 +218,8 @@ properties:
       `Class.TextChannel|TextChannels` even if
       `Class.TextChatService.CreateDefaultTextChannels|CreateDefaultTextChannels`
       is true.
+      
+      Messages from different TextChannels can be separated into different tabs in the chat window using `Class.ChannelTabsConfiguration`.
     code_samples: []
     type: bool
     tags: []