addition to authmeth-17 appendix B

I realized this morning that I hadn't yet documented the substantive
changes to RFC 2251 that are part of authmeth.  Here is the text I have
added to authmeth -18 to document these changes:

B.1. Changes Made to RFC 2251

This section summarizes the substantive changes made to sections 4.2.1
and 4.2.2 of RFC 2251 by this document.  Additional substantive changes
to section 4.2.1 of RFC 2251 are also documented in [Protocol].

B.1.1. Section 4.2.1 (Sequencing of the Bind Request)

- Paragraph 1: Removed the sentence, "If at any stage the client wishes
to abort the bind process it MAY unbind and then drop the underlying
connection."  The Unbind operation still permits this behavior, but it
is not documented explicitly.

- Clarified that the session is moved to an anonymous state upon
receipt of the BindRequest PDU and that it is only moved to a
non-anonymous state if and when the Bind request is successful. 

B.1.2. Section 4.2.2 (Authentication and Other Security Services)

- RFC 2251 states that anonymous authentication MUST be performed using
the simple bind method. This specification defines the anonymous
authentication mechanism of the simple bind method and requires all
conforming implementations to support it.  Other authentication
mechanisms producing anonymous authentication and authorization state
may also be implemented and used by conforming implementations.

Roger