[NNTP] Article number wording

[Steve Walker]

Russ Allbery wrote:

>No matter what we say or don't say in this draft, you're still going to
>have serious problems in two years with regular news reader clients.
>

I think that the clients that currently don't support 64 bit numbers 
will be fixed soon since it's a very easy process.  That is, if the RFC 
doesn't expressly forbid 64 bit numbers.  If the new RFC forbids 64 bit 
numbers then the client developers will have to choose between being 
non-compliant and actually working on all servers.  This is a potential 
mess.

Steve.