Add mirror of KVX format specification

[NotAFile]

The original link went down. It should be simple to extract the relevant parts out of the slab6 readme again

Edit: waybackmachine capture: https://web.archive.org/web/20100102023608/http://mystaddict.tlayeh.com/Computer%20Camp/Slab6/slab6.txt

[xtreme8000]

How is this relevant to the protocol

[NotAFile]

Well, it was on the protocol page before, the link just died. And it makes sense to have this on the page, in the "additional info" section.