Update "Building Skills in Object-Oriented Design" (#5301)

* Replace PDF version 2.1.1 with 2.2.1 for Python 2.
* Add the PDF version for Python 3.
* Add the current edition (HTML).

books/free-programming-books.md

@@ -2416,7 +2416,9 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Beej's Guide to Python Programming - For Beginners](http://beej.us/guide/bgpython/) - B. Hall (HTML,PDF)
 * [Biopython](http://biopython.org/DIST/docs/tutorial/Tutorial.pdf) (PDF)
 * [Build applications in Python the antitextbook](http://github.com/thewhitetulip/build-app-with-python-antitextbook) (3.x) (HTML, PDF, EPUB, Mobi)
-* [Building Skills in Object-Oriented Design (Python)](https://web.archive.org/web/20190914230227/http://www.itmaybeahack.com/book/oodesign-python-2.1/latex/BuildingSkillsinOODesign.pdf) - Steven F. Lott (PDF) (2.1.1)
+* [Building Skills in Object-Oriented Design, V4](https://slott56.github.io/building-skills-oo-design-book/build/html/) - Steven F. Lott (3.7)
+  * [Building Skills in Object-Oriented Design, Release 2.2.1](https://web.archive.org/web/20150824204101/http://buildingskills.itmaybeahack.com/book/oodesign-python-2.2/latex/BuildingSkillsinOODesign.pdf) - Steven F. Lott (PDF) (2.2.1)
+  * [Building Skills in Object-Oriented Design, Release 3.1](https://web.archive.org/web/20160322093622/http://buildingskills.itmaybeahack.com/book/oodesign-3.1/latex/BuildingSkillsinObject-OrientedDesign.pdf) - Steven F. Lott (PDF) (3.1)
 * [Building Skills in Python](https://web.archive.org/web/20190918094202/http://www.itmaybeahack.com/book/python-2.6/latex/BuildingSkillsinPython.pdf) - Steven F. Lott (PDF) (2.6)
 * [Code Like a Pythonista: Idiomatic Python](https://web.archive.org/web/20180411011411/http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html) - David Goodger
 * [CodeCademy Python](https://www.codecademy.com/learn/python)