bug-fix: Fix feedback form texts (#920)

Fixes: [AC-986](https://sendbird.atlassian.net/browse/AC-986)

[AC-986]:
https://sendbird.atlassian.net/browse/AC-986?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Author: chohongm

src/ui/Label/stringSet.ts

@@ -219,8 +219,8 @@ const stringSet = {
     EDIT_COMMENT: 'Edit Comment',
     REMOVE_FEEDBACK: 'Remove Feedback',
     // Feedback modal title
-    FEEDBACK_MODAL_TITLE: 'Please write a comment about your rating (optional)',
-    FEEDBACK_CONTENT_PLACEHOLDER: 'Feedback text',
+    FEEDBACK_MODAL_TITLE: 'Provide additional feedback (optional)',
+    FEEDBACK_CONTENT_PLACEHOLDER: 'Leave a comment',
     BUTTON__REMOVE_FEEDBACK: 'Remove feedback',
   },
 };