doc: markup stdin as tech role

Co-authored-by: Roberto Abdelkader Martínez Pérez <robertomartinezp@gmail.com>

docs/source/examples/index.rst

@@ -176,7 +176,7 @@ If you need to write more complex actions, you can leverage multiline commands:
 .. warning::
 
     Be aware of the **"-"** at the end of the ``kapow route add`` command.
-    It tells ``kapow route add`` to read commands from ``stdin``.
+    It tells ``kapow route add`` to read commands from :tech:`stdin`.
 
 .. warning::