bpo-24755: Document asyncio.wrap_future (GH-603) (GH-2019)

(cherry picked from commit 824f687)

Author: Mariatta

Doc/library/asyncio-task.rst

@@ -540,6 +540,11 @@ Task functions
 
    .. deprecated:: 3.4.4
 
+.. function:: wrap_future(future, \*, loop=None)
+
+   Wrap a :class:`concurrent.futures.Future` object in a :class:`Future`
+   object.
+
 .. function:: gather(\*coros_or_futures, loop=None, return_exceptions=False)
 
    Return a future aggregating results from the given coroutine objects or