It appears that the documentation was HTML files, but Carl didn't make it so you could click through to them without going through a form until version 2. Hence archive.org couldn't scrape it until then:
https://web.archive.org/web/19981212020708/http://rebol.com/
If it had been a .PDF or something, then someone might have a downloaded a copy and archived it along with the executable. But I'd guess unless Carl himself has a copy of the source of his old website somewhere, it's gone.
More likely you could find a Rebol 1 executable someone has around. Though even that might not be as easy to find as one would think.
I was reading about some of the design choices in REBOL, and came upon Joe Marshall's writings where he talks about the changes between REBOL 1 and 2 (missing continuations, changed scoping rules, absence of tail recursion, etc.)
If you haven't gotten a chance to read my own most recent thoughts on what binding/scoping can or should be:
Rebol And Scopes: Well, Why Not?
That points to the directions I myself want to keep exploring. (I've been playing hooky for a couple months and not programming. But have been taking proactive steps like sending my "work" laptop in for its necessary repairs... and am going to arrange for a place to retreat and design/code for a while.)
P.S. Please feel free to introduce yourself...