feat: testing book to added to ```books/free-programming-books-subjects.md``` (#11788)

* feat: added book

* fix: book name

* fix: trailing slash

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

Co-authored-by: Eric Hellman <eric@hellman.net>

---------

Co-authored-by: Eric Hellman <eric@hellman.net>

books/free-programming-books-subjects.md

@@ -868,6 +868,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Crypto 101 - Crypto for everyone](https://www.crypto101.io)
 * [Cryptography](https://en.wikibooks.org/wiki/Cryptography) - Wikibooks (HTML) *(:construction: in process)*
 * [CryptoParty Handbook](https://unglue.it/work/141611/)
+* [Fuzzing Book](https://www.fuzzingbook.org) - Andreas Zeller, Rahul Gopinath, Marcel Böhme, Gordon Fraser, Christian Holler (HTML)
 * [Gray Hat Hacking: The Ethical Hacker's Handbook](https://pages.cs.wisc.edu/~ace/media/gray-hat-hacking.pdf) - Allen Harper, Jonathan Ness, Chris Eagle, Shon Harris, Gideon Lenkey, Terron Williams (PDF)
 * [Handbook of Applied Cryptography](https://cacr.uwaterloo.ca/hac/index.html)
 * [How HTTPS works](https://howhttps.works) - dnsimple