Stateful Retry section needs example

[fmbenhassine]

Glenn Renfro opened BATCH-2645 and commented

This section has no example. It could use one (or more) to show how to inject
RetryContextCache into RetryTemplate and passing the RecoveryCallback to RetryOperations

This was originally created against Spring Batch (see spring-projects/spring-batch#958). Since Spring Batch docs do not include the retry docs anymore, I'm transferring the issue here.