bpo-33649: Add high-level APIs cheat-sheet (GH-9319)

diff --git a/Doc/library/asyncio-stream.rst b/Doc/library/asyncio-stream.rst
index 80b7625..29163a2 100644
--- a/Doc/library/asyncio-stream.rst
+++ b/Doc/library/asyncio-stream.rst
@@ -10,6 +10,8 @@
 network connections.  Streams allow sending and receiving data without
 using callbacks or low-level protocols and transports.
 
+.. _asyncio_example_stream:
+
 Here is an example of a TCP echo client written using asyncio
 streams::