I don't think you can link communities like that ? Or maybe it's only supported in some clients / instances. My understanding is that you need to link them by using the usual markdown link syntax (or the link button below the editor) and input /c/[email protected] as the link target.
Like this:
[anarchychess](/c/[email protected])
Which will render like this:
Note however that I've had some problems with this previously. I suspect that the first time someone tries to access a remote community from whatever instance you're on, your instance runs some heavy API queries which are prone to failure if either instance is under heavy load.
Neat, good to know!