Add missing `NL` in outer wrapper specification.
C-tor adds a newline between the superencrypted-string and the
"signature"
that follows. This updates the spec to be consistent with
c-tor's behavior.
Note: The The resulting document does not end with a newline character
comment refers to the plaintext of the middle document not ending in a
newline character.
Signed-off-by: Gabriela Moldovan gabi@torproject.org