asyncio doc: oh, asyncio module has its own Future class

Improve also wait() documentation: mention that the first parameter is a
sequence
diff --git a/Doc/library/asyncio.rst b/Doc/library/asyncio.rst
index 76e26c0..e00f6ce 100644
--- a/Doc/library/asyncio.rst
+++ b/Doc/library/asyncio.rst
@@ -24,8 +24,8 @@
 * concrete support for TCP, UDP, SSL, subprocess pipes, delayed calls, and
   others (some may be system-dependent);
 
-* a Future class that mimicks the one in the :mod:`concurrent.futures` module,
-  but adapted for use with the event loop;
+* a :class:`Future` class that mimicks the one in the :mod:`concurrent.futures`
+  module, but adapted for use with the event loop;
 
 * coroutines and tasks based on ``yield from`` (:PEP:`380`), to help write
   concurrent code in a sequential fashion;