Do not document unused symbols

Do not document unused symbols

The macro KRB5_KEYUSAGE_PA_REFERRAL was defined in an early revision
of draft-ietf-krb-wg-kerberos-referrals but did not make it into
RFC 6806.  We retain the definition so as to not break code implementing
the early draft, but need not document it.

Likewise, the krb5_octet_data structure and krb5_free_octet_data routine
are marked as having been originally introduced for PKINIT and "Do not
use this."  They are in fact unused, and should not be documented, but
the actual definitions must remain for compatibility.

ticket: 7489 (new)
tags: pullup
target_version: 1.11