Add link for Tsang acknowledgment

Author: hollasch

books/acknowledgments.md.html

@@ -30,7 +30,7 @@
   - Ben Kerl
   - Benjamin Summerton
   - Bennett Hardwick
-  - Benny Tsang
+  - [Benny Tsang](https://bthtsang.github.io/)
   - Dan Drummond
   - [David Chambers](https://github.com/dafhi)
   - David Hart