docs: fix example, fixes #173
diff --git a/documentation/shortintro.rst b/documentation/shortintro.rst
index 8f33a68..02385d9 100644
--- a/documentation/shortintro.rst
+++ b/documentation/shortintro.rst
@@ -44,9 +44,9 @@
     >>> ser.is_open
     False
 
-Also supported with context manager::
+Also supported with :ref:`context manager <context-manager>`::
 
-    serial.Serial() as ser:
+    with serial.Serial() as ser:
         ser.baudrate = 19200
         ser.port = 'COM1'
         ser.open()