Update README.md

Author: AnghelLeonard

HibernateSpringBootCountSQLStatements/README.md

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 **Output example (when the number of expected SQLs is not equal with the reality an exception is thrown):**\
 ![](https://github.com/AnghelLeonard/Hibernate-SpringBoot/blob/master/HibernateSpringBootCountSQLStatements/sample.png)
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+<a href="https://leanpub.com/java-persistence-performance-illustrated-guide"><p align="center"><img src="https://github.com/AnghelLeonard/Hibernate-SpringBoot/blob/master/Java%20Persistence%20Performance%20Illustrated%20Guide.jpg" height="410" width="350"/></p></a>