docs: Add asyncio source code links (GH-16640)
diff --git a/Doc/library/asyncio-subprocess.rst b/Doc/library/asyncio-subprocess.rst
index bd92257..1d87d2f 100644
--- a/Doc/library/asyncio-subprocess.rst
+++ b/Doc/library/asyncio-subprocess.rst
@@ -6,6 +6,11 @@
Subprocesses
============
+**Source code:** :source:`Lib/asyncio/subprocess.py`,
+:source:`Lib/asyncio/base_subprocess.py`
+
+----------------------------------------
+
This section describes high-level async/await asyncio APIs to
create and manage subprocesses.