2.12. Update Section 5.3.19.3 - Encryption/Key Agreement Key Pair Types

The following section clarifies the use of the Encryption/Key Agreement Key Pair Types on referencing elliptic curves.

Insert this note at the end of Section 5.3.19.3 of [RFC4210]:

Note: In case several elliptic curves are supported, several id-ecPublicKey elements as defined in [RFC5480] need to be given, one per named curve.