docs: fix link to define option

fixes #1823

documentation/topics/resources/code-interfaces.md

@@ -10,7 +10,7 @@ resources do
 end
 ```
 
-This simple setup now allows you to open a ticket with `Helpdesk.Support.open_ticket(subject)`. You can cause it to raise errors instead of return them with `Helpdesk.Support.open_ticket!(subject)`. For information on the options and additional inputs these defined functions take, look at the generated function documentation, which you can do in iex with `h Helpdesk.Support.open_ticket`. For more information on the code interface, read the DSL documentation: `d:Ash.Domain.Dsl.resource.interfaces`.
+This simple setup now allows you to open a ticket with `Helpdesk.Support.open_ticket(subject)`. You can cause it to raise errors instead of return them with `Helpdesk.Support.open_ticket!(subject)`. For information on the options and additional inputs these defined functions take, look at the generated function documentation, which you can do in iex with `h Helpdesk.Support.open_ticket`. For more information on the code interface, read the DSL documentation: `d:Ash.Domain.Dsl.resources.resource.define`.
 
 ## Code interfaces on the resource