add a book in javascript session

**Book:** Maintainable Javascript
**Author:** Nicholas Zakas
**Description:** You may have definite ideas about writing code when working alone, but team development requires that everyone use the same approach. With the JavaScript practices in this book—including code style, programming tips, and automation—you will learn how to write maintainable code that other team members can easily understand, adapt, and extend.
Merge pull request #70 from pedronauck/patch-1

add a book in javascript session