Add table for mitigations that increase privacy when using revocation lists

[msporny]

We should add a table to the privacy considerations that lists all of the mitigations that increase privacy when using status lists (or really, any issuer-provided resource). It could look something along the following lines:

Mitigation	Attacker	Implementer	Cost	Attack	Defense
K-anonymity	issuer	issuer	$	Issuer tracking individual subjects.	Issuer places status of subjects into a large set that provides statistically significant k-anonymity.
CDN	issuer	issuer	$	Issuer using access metrics to determine subjects with high degree of confidence.	Verifier retrieves resource in a way where issuer is not contacted at all.
OHTTP	issuer	verifier	$$	Issuer using verifier identification to determine subjects with high degree of confidence	Verifier retrieves resource and caches in a way that blinds issuer to party asking.
Holder delivery	issuer	holder	$$	Issuer using statistical probability to determine subjects	Verifier retrieves resource in a way where issuer is not contacted at all.
Watchdog	issuer	holder	$$$	Issuer reduces k-anonymity to an unacceptable value	Digital wallet services provide watchdog services for infrequently used resource identifiers.