Added English book Mastering the Lightning Network

books/free-programming-books-subjects.md

@@ -147,6 +147,7 @@ Books that cover a specific programming language can be found in the  [BY PROGRA
 * [IBM Blockchain: The Founder’s Handbook, Third Edition](https://www.ibm.com/downloads/cas/GZPPMWM5) - Antonio Banda, Matthew Hamilton, Eileen Lowry, John Widdifield et al. (PDF)
 * [Mastering Bitcoin - Unlocking digital currencies (2017), 2nd Edition](https://github.com/bitcoinbook/bitcoinbook) - Andreas M. Antonopoulos (AsciiDoc)
 * [Mastering Ethereum (2018), 1st Edition](https://github.com/ethereumbook/ethereumbook) - Andreas M. Antonopoulos, Gavin Wood (AsciiDoc)
+* [Mastering the Lightning Network](https://github.com/lnbook/lnbook) - Andreas M. Antonopoulos, Olaoluwa Osuntokun, Rene Pickhardt (AsciiDoc)
 * [Playtime with Hyperledger Composer](https://schadokar.dev/ebooks/playtime-with-hyperledger-composer/) - Shubham Chadokar (PDF)