Merge pull request #2 from Musbi8788/Musbi8788-added_pdf

fix Biopython Tutorial and Cookbook PDF build issue for Hacktoberfest…

Author: Musbi8788

books/free-programming-books-langs.md

@@ -1986,7 +1986,7 @@ Books on general-purpose programming that don't focus on a specific language are
 * [Automate the Boring Stuff with Python, 3nd Edition: Practical Programming for Total Beginners](https://automatetheboringstuff.com/3e/) - Al Sweigart (HTML) (CC BY-NC-SA)
 * [Beej's Guide to Python Programming - For Beginners](http://beej.us/guide/bgpython/) - Brian "Beej Jorgensen" Hall (HTML,PDF)
 * [Beyond the Basic Stuff with Python](https://inventwithpython.com/beyond/) - Al Sweigart (3.x)
-* [Biopython Tutorial and Cookbook](https://biopython.org/wiki/Documentation) (HTML)
+* [Biopython Tutorial and Cookbook](https://biopython.org/wiki/Documentation) (HTML, PDF) 
 * [Build applications in Python the antitextbook](http://github.com/thewhitetulip/build-app-with-python-antitextbook) (3.x) (HTML, PDF, EPUB, Mobi)
 * [Building Data Products: The Ultimate Guide](https://resources.montecarlodata.com/c/ebook-building-data-products?x=gEwOdf) (HTML, EPUB)
 * [Building Skills in Object-Oriented Design, V4](https://slott56.github.io/building-skills-oo-design-book/build/html/) - Steven F. Lott (3.7)