Added a new pandas book (HTML) (#7183)

* Added a new pandas book (html)

* order

* removed extra whitespace

* Update books/free-programming-books-langs.md

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

books/free-programming-books-langs.md

@@ -1970,6 +1970,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 
 #### Pandas
 
+* [Best Pandas Tutorial \| Learn with 50 Examples](https://www.listendata.com/2017/12/python-pandas-tutorial.html) - Ekta Aggarwal (HTML)
 * [Learn Pandas](https://bitbucket.org/hrojas/learn-pandas) - Hernan Rojas (0.18.1)
 * [pandas: powerful Python data analysis toolkit](https://pandas.pydata.org/docs) - Wes McKinney, the Pandas Development Team (HTML, PDF)