Update intro_onnx.py (#3033)

Add onnxruntime dependency

Author: labintsev

beginner_source/onnx/intro_onnx.py

@@ -39,13 +39,14 @@
 
   - `ONNX <https://onnx.ai>`_ standard library
   - `ONNX Script <https://onnxscript.ai>`_ library that enables developers to author ONNX operators,
-    functions and models using a subset of Python in an expressive, and yet simple fashion.
+    functions and models using a subset of Python in an expressive, and yet simple fashion
+  - `ONNX Runtime <https://onnxruntime.ai>`_ accelerated machine learning library.
 
 They can be installed through `pip <https://pypi.org/project/pip/>`_:
 
 .. code-block:: bash
 
-  pip install --upgrade onnx onnxscript
+  pip install --upgrade onnx onnxscript onnxruntime
 
 To validate the installation, run the following commands: