Document deprecations of org.springframework.boot.loader.archive.Archive.iterator()

[wilkinsona]

org.springframework.boot.loader.archive.Archive.iterator() was deprecated in 2.3 but Archive implements Iterable<Archive.Entry> which defines the iterator() method. If we remove the deprecated method it'll become present in undeprecated form as it'll be inherited from Iterable. I think we either need to deprecate all three methods defined by Iterable so that Archive can stop extending it in the future or we need to undeprecate iterator().

[philwebb]

My preference would be to deprecate all three.