add reference info to session-1

Author: phanukaev

docs/session-1.html

@@ -17,7 +17,10 @@ Hopefully by the end of this session you will have seen enough to be able
 to read the [[https://docs.python.org/3/tutorial/index.html][Python Tutorial]] on your own.
 The first 6 chapters should suffice for an introduction.
 The [[https://docs.python.org/3/library/csv.html][CSV package reference]] is quite short and can be read in 20-30 minutes.
-For general 
+For general help there is also the
+[[https://docs.python.org/3/library/index.html][library reference]] (may be hard to read) or the slightly easier but less
+comprehensive [[https://www.w3schools.com/python/python_reference.asp][reference on w3schools]].
+
 
 
 * The Problem Statement