fixed xref in starknet-by-example/storage.adoc

Author: LandauRaz

components/Starknet/modules/guides/pages/starknet-by-example/storage.adoc

@@ -36,7 +36,7 @@ mod Contract {
 Both contracts above generate identical Sierra code. The compiler only generates code for storage variables that are actually used in contract functions. Declaring unused storage variables has no impact on contract size or gas costs.
 ====
 
-For more complex data structures, see xref:starknet-by-example/custom-types#storing_custom_types[Storing Custom Types].
+For more complex data structures, see xref:starknet-by-example/custom-types.adoc#storing_custom_types[Storing Custom Types].
 
 ### Storage Space (advanced)