Remove patch. not free

Co-authored-by: David Ordás <[email protected]>

Author: eshellman

Diff for: books/free-programming-books-langs.md

@@ -407,7 +407,6 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 ### Blockchain
 
 * [Blockchain for Dummies](https://www.ibm.com/downloads/cas/36KBMBOG) - Manav Gupta (PDF)
-* [Introducing Ethereum and Solidity](https://the-eye.eu/public/Books/qt.vidyagam.es/library/humble-bitcoin-bundle/Introducing%20Ethereum%20and%20Solidity_%20Foud%20Blockchain%20Programming%20for%20Beginners/Introducing%20Ethereum%20and%20Solidity_%20Foundatiin%20Programming%20for%20Beginners%20-%20Chris%20Dannen.pdf) - Chris Dannen (PDF)
 
 
 ### C