Rather than updating the reference from RFC3330 to RFC6890, by the way, RFC6890 itself has been updated by RFC8190. Further, numerous RFCs have updated the registry since its creation by RFC5736 and its expansion by RFC6890. Therefore, I think it would be better to directly reference the "IANA IPv4 Special-Purpose Address Registry" at its permanent URL ( https://www.iana.org/assignments/iana-ipv4-special-registry ), instead of referencing the RFC that created the registry. Note the registry itself references, RFC5736, RFC6980, and RFC8190 for its registry policies.
Also, I think it would be useful to add a reference to RFC6598 "IANA-Reserved IPv4 Prefix for Shared Address Space" to subsection 2, where RFC1918 is discussed. Note RFC6598 is distinct from RFC1918 but has a similar purpose.