Use correct directive and name.
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index 7326712..8037bfe 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -99,7 +99,7 @@
                   yield element
 
 
-.. function:: itertools.chain.from_iterable(iterable)
+.. classmethod:: chain.from_iterable(iterable)
 
    Alternate constructor for :func:`chain`.  Gets chained inputs from a
    single iterable argument that is evaluated lazily.  Equivalent to::