Contracts: COMPLEXITY.md (#905)

* Initial sketch.

* More work.

* Grammar.

* Fix.

* Fix grammar.

substrate/srml/contract/src/lib.rs

@@ -270,7 +270,7 @@ impl<T: Trait> Module<T> {
 
 	/// Create a new contract, optionally transfering some balance to the created account.
 	///
-	/// Creation is executed as follows:ExecutionContext
+	/// Creation is executed as follows:
 	///
 	/// - the destination address is computed based on the sender and hash of the code.
 	/// - account is created at the computed address.

substrate/srml/contract/src/vm/runtime.rs

@@ -89,6 +89,10 @@ pub(crate) fn to_execution_result<E: Ext>(
 	}
 }
 
+// ***********************************************************
+// * AFTER MAKING A CHANGE MAKE SURE TO UPDATE COMPLEXITY.MD *
+// ***********************************************************
+
 // TODO: ext_balance, ext_address, ext_callvalue, etc.
 
 // Define a function `fn init_env<E: Ext>() -> HostFunctionSet<E>` that returns