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