Doc on flatten

spec/06.standard_library.tex

@@ -335,7 +335,7 @@ fresh list if images in the same order.}
   "\lstinline|Some (v)|" otherwise, where "\lstinline|v|"~--- the first value to satisfy "\lstinline|f|".
 }
 
-\descr{\lstinline|fun flatten (l)|}{Flattens a list of lists into a regular list. The order of elements is preserved in both senses.}
+\descr{\lstinline|fun flatten (l)|}{Flattens an arbitrary nesting of lists into a regular list. The order of elements is preserved in both senses.}
 
 \descr{\lstinline|fun zip (a, b)|}{Zips a pair of lists into the list of pairs. Does not work for lists of different lengths.}