Spring Improve documentation for @Autowired/@Value in @Configuration classes

Original： Otherwise, @Autowired and @Value do not work on the configuration class itself, since it is being created as a bean instance too early.

I think this statement is not accurate enough. @Autowired actually works, if the priority of the definition of BeanPostProcessor through @Bean lower than AutowiredAnnotationBeanPostProcessor. So, I think we can adjust this description.

Comment From: sbrannen

This has been merged into master.

Thanks