minor edit: reference change for IANA

The reference IANA

    # the value should either be a charset registered with the Internet
    # Assigned Numbers Authority [IANA] or start with X- 

which points to

    Internet Assigned Numbers Authority. Character Sets. 
    See ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets. 

should instead point to

     RFC 2278 "IANA Charset Registration Procedures." N. Freed, J. Postel.
     January 1998. (Also BCP0019) (Status: BEST CURRENT PRACTICE)

However, to actually give a reference, RFC 2046 defines the charset
parameter, while RFC 2278 merely describes the registration process
(and then points to the list of registered values.)

Larry
-- 
http://www.parc.xerox.com/masinter