Fix Trac #1909: type of map in docs

docs/users_guide/ghci.xml

@@ -1437,7 +1437,7 @@ as = 'b' : 'c' : (_t1::[Char])
 <programlisting>
 import Prelude hiding (map)
 
-map :: (a->b) -> a -> b
+map :: (a->b) -> [a] -> [b]
 map f [] = []
 map f (x:xs) = f x : map f xs
 </programlisting>