Update readme.md

readme.md

@@ -51,6 +51,7 @@ The term was coined by Eric Evans in his book of the same title.
 - [Secure by Design (early access)](https://www.manning.com/books/secure-by-design?a_aid=danbjson&a_bid=0b3fac80) - Shows how to use Domain-Driven Design to avoid security vulnerabilities.
 - [Applying Domain Driven Design with CQRS and Event Sourcing](https://buildplease.com/pages/now-what/) - A walkthrough of using EventStorming and other modeling techniques to build a CQRS and Event Sourcing-based prototype for a fictional business domain.
 - [Versioning in an Event Sourced System](https://leanpub.com/esversioning) - Have you had troubles with versioning an Event Sourced system? Just getting into a new Event Sourced system for the first time? This book is the definitive guide of how to handle versioning over long periods of time.
+- [Writing Great Specifications](https://www.manning.com/books/writing-great-specifications) - Writing Great Specifications is an example-rich tutorial that teaches you how to write good Gherkin specification documents that take advantage of Specification by Example's benefits. 
 
 ## Training Courses