docs: Add asyncio source code links (GH-16640)
diff --git a/Doc/library/asyncio-sync.rst b/Doc/library/asyncio-sync.rst
index cc8c29d..f080b03 100644
--- a/Doc/library/asyncio-sync.rst
+++ b/Doc/library/asyncio-sync.rst
@@ -6,6 +6,10 @@
Synchronization Primitives
==========================
+**Source code:** :source:`Lib/asyncio/locks.py`
+
+-----------------------------------------------
+
asyncio synchronization primitives are designed to be similar to
those of the :mod:`threading` module with two important caveats: