Fix some typos in the tutorial

docs/tutorial/interfaces.rst

@@ -282,11 +282,13 @@ which reads a number from the console, returning a value of the form
 
 .. code-block:: idris
 
+    import Data.Strings
+
     readNumber : IO (Maybe Nat)
     readNumber = do
       input <- getLine
       if all isDigit (unpack input)
-         then pure (Just (cast input))
+         then pure (Just (stringToNatOrZ input))
          else pure Nothing
 
 If we then use it to write a function to read two numbers, returning

docs/tutorial/typesfuns.rst

@@ -753,12 +753,8 @@ For more details of the functions available on ``List`` and
 
 -  ``libs/base/Data/List.idr``
 
--  ``libs/base/Data/List.idr``
-
 -  ``libs/base/Data/Vect.idr``
 
--  ``libs/base/Data/VectType.idr``
-
 Functions include filtering, appending, reversing, and so on.
 
 Aside: Anonymous functions and operator sections
@@ -1052,7 +1048,7 @@ name. For example, a pair type could be defined as follows:
         fst : a
         snd : b
 
-Using the ``class`` record from earlier, the size of the class can be
+Using the ``Class`` record from earlier, the size of the class can be
 restricted using a ``Vect`` and the size included in the type by parameterising
 the record with the size.  For example: