adds ref to selective disclosure (#84)

Signed-off-by: Kevin Griffin <[email protected]>

spec/spec.md

@@ -440,7 +440,7 @@ Given that there is no top-level UUID, `u`, field in an ACDC, then knowledge of
 
 ### Private ACDC
 
-Given a top-level UUID, `u`, field, whose value has sufficient cryptographic entropy, then the top-level SAID, `d`, field of an ACDC may provide a secure cryptographic digest that blinds the contents of the ACDC [[48]]. An adversary when given both the Schema of the ACDC and the top-level SAID, `d`, field, is not able to discover the remaining contents of the ACDC in a computationally feasible manner such as through a rainbow table attack [[30]] [[31]]. Therefore, the top-level, UUID, `u`, field may be used to securely blind the contents of the ACDC notwithstanding knowledge of the Schema and top-level, SAID, `d`, field.  Moreover, a cryptographic commitment to that that top-level SAID, `d`, field does not provide a fixed point of correlation to the other ACDC field values themselves unless and until there has been a disclosure of those field values. Thus, an ACDC with a sufficiently high entropy top-level UUID, `u`, field may be considered a private (confidential) ACDC. enables a verifiable commitment to the top-level SAID of a private ACDC to be made prior to the disclosure of the details of the ACDC itself without leaking those contents. This is called Partial Disclosure. Furthermore, the inclusion of a UUID, `u`, field in a block also enables Selective Disclosure mechanisms described later in the section on Selective Disclosure.
+Given a top-level UUID, `u`, field, whose value has sufficient cryptographic entropy, then the top-level SAID, `d`, field of an ACDC may provide a secure cryptographic digest that blinds the contents of the ACDC [[48]]. An adversary when given both the Schema of the ACDC and the top-level SAID, `d`, field, is not able to discover the remaining contents of the ACDC in a computationally feasible manner such as through a rainbow table attack [[30]] [[31]]. Therefore, the top-level, UUID, `u`, field may be used to securely blind the contents of the ACDC notwithstanding knowledge of the Schema and top-level, SAID, `d`, field.  Moreover, a cryptographic commitment to that that top-level SAID, `d`, field does not provide a fixed point of correlation to the other ACDC field values themselves unless and until there has been a disclosure of those field values. Thus, an ACDC with a sufficiently high entropy top-level UUID, `u`, field may be considered a private (confidential) ACDC. enables a verifiable commitment to the top-level SAID of a private ACDC to be made prior to the disclosure of the details of the ACDC itself without leaking those contents. This is called Partial Disclosure. Furthermore, the inclusion of a UUID, `u`, field in a block also enables Selective Disclosure mechanisms described later in the section on [Selective Disclosure](#selective-disclosure).
 
 ### Metadata ACDC