docs: use absolute page URI

This allows us to migrate to any framework that uses normal uri's
We just need to strip all .md endings in a simple grep command

lib/modules/clan/interface.nix

@@ -237,7 +237,7 @@ in
       description = ''
         The `Inventory` submodule.
 
-        For details see the [Inventory](./inventory.md) documentation.
+        For details see the [Inventory](/reference/options/clan_inventory.md) documentation.
       '';
     };