Warhammer 40k - Lexicanum:Related changes
Related changes on an article page
The Related changes tool can be accessed from the Tools tab at the left side of the screen.
Related changes from the Special pages overview
Since you have not directly accessed the Related changes tool from a specific article page you now have to enter the actual article page name you want to use the tool for.
Here you also have the option to specify the Namespace in which the article page name should be searched.
You can also directly access the tool by clicking here.
More on the Related changes Wikimedia tool can be found here.