Show completed Main

Resolves #30

README.adoc

 `src/main/java/hello/Application.java`
 [source,java]
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-include::initial/src/main/java/hello/Application.java[]
+include::complete/src/main/java/hello/Application.java[]
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 include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/spring-boot-application.adoc[]