[ietf-charsets] Fix links for International Register of Coded Charater Sets to be Used with Escape Sequences

[Martin J. Dürst]

Dear IANA,

I'm writing to you as the designated Expert for Character Sets
(https://www.iana.org/assignments/character-sets/character-sets.xhtml).

I found out that the links 
(https://www.itscj-ipsj.jp/custom_contents/cms/linkfile/ISO-IR.pdf) for 
the text
[ISO-IR: International Register of Escape Sequences]
appearing close to 80 times on the above page are to a site that no 
longer exists.

The reason seems to be that at some point in time,
www.itscj-ipsj.jp was moved to itscj.ipsj.or.jp, and the site was 
reorganized.

I found the relevant document at
https://itscj.ipsj.or.jp/english/vbcqpr00000004qn-att/ISO-IR.pdf
so this is the link you should use.

I can also contact ITSCJ to tell them that we depend on their registry, 
and they shouldn't move it around without notifying us. But my guess is 
that they will agree but later forget. This happens on average in 
organizations around the world.

Regards,    Martin.