Document that circular dependencies should be avoided in AOT mode

[sbrannen]

Add a new subsection to the Best Practices section to explain that circular dependencies should be avoided for AOT-proccessed Spring applications.

Specifically, circular dependencies that work in standard JVM mode (such as @Autowired fields and methods) do not work in AOT mode unless a @Lazy resolution proxy is used.

See MockitoSpyBeanAndCircularDependenciesWithLazyResolutionProxyIntegrationTests for an example.