Fix 01-The-Function-Monad.md typo (#613)

Fix a wrongly named parameter "argument" into correct name "input", which corresponds to the lambda parameter.

21-Hello-World/05-Application-Structure/src/02-MTL/01-Foundations.md/01-The-Function-Monad.md

@@ -363,7 +363,7 @@ class Functor ((->) inputType) where
          (originalOutputType -> newOutputType) ->
          (inputType -> originalOutputType) -> (inputType -> newOutputType)
   map originalToNew f = (\input ->
-    let originalOutput = f argument
+    let originalOutput = f input
     in originalToNew originalOutput)
 
 class (Functor ((->) inputType)) <= Apply ((->) inputType) where