[JAVA-2306] Moved articles from spring-persistence-simple

* https://www.baeldung.com/the-persistence-layer-with-spring-and-jpa went into spring-jpa-2

* https://www.baeldung.com/hibernate-5-spring went to spring-jpa-2

* https://www.baeldung.com/transaction-configuration-with-jpa-and-spring went to spring-jpa-2

* https://www.baeldung.com/persistence-layer-with-spring-and-hibernate went to spring-jpa-2

* https://www.baeldung.com/simplifying-the-data-access-layer-with-spring-and-java-generics went to spring-jpa-2

* https://www.baeldung.com/the-persistence-layer-with-spring-data-jpa went to spring-data-jpa-repo-2

* https://www.baeldung.com/spring-data-jpa-query went to spring-data-jpa-query-2

* https://www.baeldung.com/spring-jdbc-jdbctemplate moved to spring-jdbc

* Removed spring-persistence-simple module as all articles have been moved

persistence-modules/spring-persistence-simple/README.md

@@ -1,25 +0,0 @@
-=========
-
-## Spring Persistence Example Project
-
-
-### Relevant Articles: 
-- [A Guide to JPA with Spring](https://www.baeldung.com/the-persistence-layer-with-spring-and-jpa)
-- [Bootstrapping Hibernate 5 with Spring](http://www.baeldung.com/hibernate-5-spring)
-- [The DAO with Spring and Hibernate](https://www.baeldung.com/persistence-layer-with-spring-and-hibernate)
-- [Simplify the DAO with Spring and Java Generics](https://www.baeldung.com/simplifying-the-data-access-layer-with-spring-and-java-generics)
-- [Transactions with Spring and JPA](https://www.baeldung.com/transaction-configuration-with-jpa-and-spring)
-- [Introduction to Spring Data JPA](http://www.baeldung.com/the-persistence-layer-with-spring-data-jpa)
-- [Spring Data JPA @Query](http://www.baeldung.com/spring-data-jpa-query)
-- [Spring JDBC](https://www.baeldung.com/spring-jdbc-jdbctemplate)
-- [Transaction Propagation and Isolation in Spring @Transactional](https://www.baeldung.com/spring-transactional-propagation-isolation)
-
-### Eclipse Config 
-After importing the project into Eclipse, you may see the following error:  
-"No persistence xml file found in project"
-
-This can be ignored: 
-- Project -> Properties -> Java Persistance -> JPA -> Error/Warnings -> Select Ignore on "No persistence xml file found in project"
-Or: 
-- Eclipse -> Preferences - Validation - disable the "Build" execution of the JPA Validator 
-