Added Python tutorial at Tutorialspoint (#4908)

* Added Python tutorial at Tutorialspoint

* Update free-programming-interactive-tutorials-en.md

* Added HTML and CSS tutorials at W3Schools

* Added Python Tutorial in free programming books

free-programming-books.md

@@ -2408,6 +2408,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Python Practice Projects](http://pythonpracticeprojects.com)
 * [Python Programming](https://en.wikibooks.org/wiki/Python_Programming) - Wikibooks (2.7)
 * [Python Programming](https://upload.wikimedia.org/wikipedia/commons/9/91/Python_Programming.pdf) - Wikibooks (PDF) (2.6)
+* [Python Tutorial](https://www.tutorialspoint.com/python) - Tutorials Point
 * [Scipy Lecture Notes](http://scipy-lectures.github.io)
 * [SICP in Python](http://www-inst.eecs.berkeley.edu/~cs61a/sp12/book/) (3.2)
 * [Slither into Python: An introduction to Python for beginners](https://www.slitherintopython.com) (3.7)

free-programming-interactive-tutorials-en.md

@@ -128,10 +128,12 @@
 ### HTML / CSS
 
 * [CSS Diner](http://flukeout.github.io)
+* [CSS Tutorial](https://www.w3schools.com/css/) - W3Schools
 * [Flexbox Defense](http://flexboxdefense.com)
 * [Flexbox Froggy](http://flexboxfroggy.com)
 * [FreeCodeCamp: Responsive Web Design Course](https://www.freecodecamp.org/learn/responsive-web-design/basic-html-and-html5/)
 * [Grid Garden](https://cssgridgarden.com)
+* [HTML Tutorial](https://www.w3schools.com/html/) - W3Schools
 * [Learn by doing beginner projects](https://dash.generalassemb.ly)
 * [Learn HTML & CSS interactively](https://www.codecademy.com/learn/web)
 * [Prototyping a professional website](https://www.codecademy.com/learn/make-a-website)