Add ToC section

README.md

@@ -4,6 +4,17 @@ This project is a *thorough* introductory course
     in programming with **[Python <img height="12" style="display: inline-block" src="static/link/to_py.png">](https://www.python.org/)**.
 
 
+### Table of Contents
+
+The materials are designed to resemble a book.
+They can be viewed in a web browser
+    either statically (i.e., read-only) on [nbviewer <img height="12" style="display: inline-block" src="static/link/to_nb.png">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/tree/develop/)
+    or interactively (i.e., code can be executed) on [Binder <img height="12" style="display: inline-block" src="static/link/to_mb.png">](https://mybinder.org/v2/gh/webartifex/intro-to-python/develop?urlpath=lab).
+**Video** presentations on the content are available
+    either via the individual links to [YouTube <img height="12" style="display: inline-block" src="static/link/to_yt.png">](https://www.youtube.com) below
+    or this [playlist <img height="12" style="display: inline-block" src="static/link/to_yt.png">](https://www.youtube.com/playlist?list=PL-2JV1G3J10lQ2xokyQowcRJI5jjNfW7f).
+
+
 ### Objective
 
 The **main goal** is to **prepare** students