Offline Documetntation

I tried to create local rails documentation in a new rails project

There is no directory vendor/rails. Does this mean one must "freeze"
rails in order to generate documentation?

Hrm. Dunno. I've always had it in vendor and it's worked...

What must I do to get rake doc:rails to work?

Zip file of the 1.2.5 docs and of the 2.0 (pre-release as of oh, maybe two weeks ago).

Help yourself.

Very fine. I vaguely remember blogs about .CHM and some Firefox
sidebar offline API doc files, as well.