In the rich text editor:
@SleeplessBoy
In a comment:
[SleeplessBoy](https://chowlings.com/user/SleeplessBoy)
For Names and Avatars:
In the rich text editor:
%SleeplessBoy
In a comment:
[](https://chowlings.com/user/SleeplessBoy) [SleeplessBoy](https://chowlings.com/user/SleeplessBoy)