[Members] s/JEP/XEP/g

[Ian Paterson]

The "Standards Track" label already differentiates those protocols that are 
likely to be of general use.

> I think we need 2 repositories. We could also move historical JEPs the the
> "2nd repository". The council could decide which protocol goes to which
> repository.
>
> Otherwise we will end up with one big unmanageable repository of 500+ 
> JEP's
> soon. And i don't think this is what we want.

There are thousands of RFCs.

IMHO we don't need multiple repositories, we just need intelligent 
categories that enable developers to browse for what they need (you could 
think of each value of each category as defining a sub-repository). One 
important advantage of this approach is you don't end up having to search 
multiple repositories whenever you're not sure which repository might 
contain the protocol.

- Ian