Introduce OnSetCode type into system config trait. (#8496)

* Introduce OnSetCode type into system config trait.

* Docs.

* Fixes

* Fixes

substrate/bin/node-template/runtime/src/lib.rs

@@ -195,6 +195,8 @@ impl frame_system::Config for Runtime {
 	type SystemWeightInfo = ();
 	/// This is used as an identifier of the chain. 42 is the generic substrate prefix.
 	type SS58Prefix = SS58Prefix;
+	/// The set code logic, just the default since we're not a parachain.
+	type OnSetCode = ();
 }
 
 impl pallet_aura::Config for Runtime {