Remove reference to resolved issues in Groovy

spring-boot-samples/spring-boot-sample-web-groovy-templates/README.md

 This sample application uses Spring Boot and
-[Groovy templates](http://beta.groovy-lang.org/docs/groovy-2.3.0/html/documentation/markup-template-engine.html)
+[Groovy templates](http://beta.groovy-lang.org/docs/groovy-2.3.1/html/documentation/markup-template-engine.html)
 in the View layer. The templates for this app live in
 `classpath:/templates/`, which is the conventional location for Spring
 Boot. External configuration is available via
 "spring.groovy.template.*".
 
-The templates all use a fixed "layout" implemented anticipating
-changes in Groovy 2.3.1 using a custom `BaseTemplate` class
-(`LayoutAwareTemplate`).