* Remove dead link to "The Standard Python Library"

The link to the book "The Standard Python Library" hosted on effbot.org is dead, and I could not find another source that legally hosts that book.

* Update free-programming-books.md

The link to the book "The Standard Python Library" hosted on effbot.org is dead:

http://effbot.org/librarybook/

This change updates it to the one at archive.org.