docs: clarify that @JsonFormat also affects deserializing

[marinier]

The wiki page and javadoc only mention serialization for the @JsonFormat annotation, but it also affects deserialization. The fix should be as simple as:

wiki:
"serializing" -> "serializing and deserializing"

javadoc:
"serialized" -> "serialized and deserialized"

I realize the header of the wiki section this is in already mentions deserialization, but I think the change would still help. The javadoc doesn't mention deserialization at all.