Fix for issue #39

Verified that the build files use Java 17.
Changed the java-version attribute in the readme to 17.

Author: Jay Bryant

README.adoc

@@ -12,7 +12,7 @@ relational database.
 
 == What You Need
 
-:java_version: 1.8
+:java_version: 17
 include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/main/prereq_editor_jdk_buildtools.adoc[]
 
 include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/main/how_to_complete_this_guide.adoc[]