Update README

to remove the Java version and update the Boot version
and the Initializr link.

Author: Jay Bryant

README.adoc

@@ -1,5 +1,5 @@
 :spring_version: current
-:spring_boot_version: 2.4.3
+:spring_boot_version: 3.0.2
 :jackson: https://wiki.fasterxml.com/JacksonHome
 :SpringApplication: https://docs.spring.io/spring-boot/docs/{spring_boot_version}/api/org/springframework/boot/SpringApplication.html
 :EnableAsync: https://docs.spring.io/spring/docs/current/spring-framework-reference/html/scheduling.html#scheduling-annotation-support
@@ -27,15 +27,14 @@ operations and merge them into a single asynchronous computation.
 
 == What You Need
 
-:java_version: 1.8
 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[]
 
 [[scratch]]
 == Starting with Spring Initializr
 
-You can use this https://start.spring.io/#!type=maven-project&language=java&platformVersion=2.5.5&packaging=jar&jvmVersion=11&groupId=com.example&artifactId=async-method&name=async-method&description=Demo%20project%20for%20Spring%20Boot&packageName=com.example.async-method&dependencies=web[pre-initialized project] and click Generate to download a ZIP file. This project is configured to fit the examples in this tutorial.
+You can use this https://start.spring.io/#!type=gradle-project&language=java&platformVersion=3.0.2&packaging=jar&jvmVersion=17&groupId=com.example&artifactId=async-method&name=async-method&description=Demo%20project%20for%20Spring%20Boot&packageName=com.example.async-method&dependencies=web[pre-initialized project] and click Generate to download a ZIP file. This project is configured to fit the examples in this tutorial.
 
 To manually initialize the project: