Add class-level javadoc to HAETAE lightweight value-object classes

Matches the terse role-description style established for the Hawk,
AIMer, QR-UOV and SMAUG-T lightweight packages: HAETAEKeyParameters
describes the common base; HAETAEPublicKeyParameters and
HAETAEPrivateKeyParameters identify the role of the wrapped raw-encoded
key bytes. HAETAEParameters already carries its own class-level
javadoc (covering the three NIST level 2/3/5 parameter sets).

Complements the earlier docs sweep on the JCE-side classes (commit
43890b81e) so every HAETAE class — lightweight and JCA — now opens with
the same role description.

No logic changes.