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