docs: Add asyncio source code links (GH-16640)

(cherry picked from commit f900064ac4b35226caad7502abc8a7e64f1c0e9d)

Co-authored-by: Kyle Stanley <aeros167@gmail.com>
diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst
index 6829233..1a23661 100644
--- a/Doc/library/asyncio-task.rst
+++ b/Doc/library/asyncio-task.rst
@@ -18,9 +18,9 @@
 Coroutines
 ==========
 
-Coroutines declared with async/await syntax is the preferred way of
-writing asyncio applications.  For example, the following snippet
-of code (requires Python 3.7+) prints "hello", waits 1 second,
+:term:`Coroutines <coroutine>` declared with the async/await syntax is the
+preferred way of writing asyncio applications.  For example, the following
+snippet of code (requires Python 3.7+) prints "hello", waits 1 second,
 and then prints "world"::
 
     >>> import asyncio
@@ -238,6 +238,10 @@
     .. versionadded:: 3.7
 
 
+    .. note::
+       The source code for ``asyncio.run()`` can be found in
+       :source:`Lib/asyncio/runners.py`.
+
 Creating Tasks
 ==============