Further clarify the notion of a decorated type

Essentially, remove the period between the first and second statement and use a single phrase instead:

The set of decorated types of a decorator includes all bean types of the managed bean which are Java interfaces, except for <literal>java.io.Serializable</literal>. The decorator bean class and its superclasses are not decorated types of the decorator.

This is a rather cosmetic change, but can improve the readability of the section.