In the rich text editor:
@Svetlbed
In a comment:
[Svetlbed](https://chowlings.com/user/Svetlbed)
For Names and Avatars:
In the rich text editor:
%Svetlbed
In a comment:
[![Svetlbed's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/Svetlbed) [Svetlbed](https://chowlings.com/user/Svetlbed)