Fix reference link.

asio/src/doc/examples.qbk

diff --git a/asio/src/doc/examples.qbk b/asio/src/doc/examples.qbk
index a8da383..483a83d 100644
--- a/asio/src/doc/examples.qbk
+++ b/asio/src/doc/examples.qbk
@@ -34,7 +34,7 @@
 * [@../src/examples/chat/chat_server.cpp]
 
 The following POSIX-specific chat client demonstrates how to use the
-[link asio.reference.posix.stream_descriptor posix::stream_descriptor] class to
+[link asio.reference.posix__stream_descriptor posix::stream_descriptor] class to
 perform console input and output.
 
 * [@../src/examples/chat/posix_chat_client.cpp]