Document npm purpose and no guarantee for version

Author: hhorak

common

@@ -20,6 +20,11 @@ Python's elegant syntax and dynamic typing, together with its interpreted nature
 make it an ideal language for scripting and rapid application development in many areas 
 on most platforms.
 
+This container image includes an npm utility, so users can use it to install JavaScript
+modules for their web applications. There is no guarantee for any specific npm or nodejs
+version, that is included in the image; those versions can be changed anytime and
+the nodejs itself is included just to make the npm work.
+
 Usage
 ---------------------
 To build a simple [python-sample-app](https://github.com/sclorg/s2i-python-container/tree/master/{{ spec.version }}/test/setup-test-app) application