Confirm NIST SP800-38A Addendum fetches

[ronaldtse]

[%bibitem]
=== SP800-38A Addendum Recommendation for Block Cipher Modes of Operation: Three Variants of Ciphertext Stealing for CBC Mode
id:: SP800-38A-Add
docid::
  id::: SP800-38A-Add
contributor::
contributor.role:: author
contributor.person.name.initial:: M.
contributor.person.name.surname:: Dworkin
contributor.person.affiliation.organization.name:: NIST
contributor::
contributor.role:: publisher
contributor.organization.name:: National Institute of Standards and Technology
contributor.organization.abbreviation:: NIST
date::
date.type:: published
date.value:: 2010

[ronaldtse]

Leaving this to @andrew2net to define syntax, update README and update gem.

@andrew2net has confirmed that the NIST Relaton endpoint provides this document.

[andrew2net]

confirmed