Wow, funny no one thought about . he, or that fact that there's a unix/linux documentation project out there, online I forget the name but it's 10's of thousands of ppl, all contribing to a large archive of info. Open source is so cozy The best documentation/info for source learning, would be to first know what you want as a o/s, what your needs are, then you build a knowledge base around that o/s, also if you want to spread a tree structure of knowledge, pick one(me=bell labs unix), then expand from it down to whatever branches you want, then info on security, bugs, code, base(kernel), lib structure, bladity bladity bla. You get me? good. There are tons of hidden, and visible source of knowledge/info out there, that you can sure as hell help yourself too. Consume the information, and mind breed a dream. Mine is a o/s I will build someday.

But if you wanted some 0day cheat info into becoming elite, I won't be helping that. Learning from expierence is best imo, if not then go learn from the people that created, and work on the o/s's. Or if you want to try harder go into the hardware side of things. That's all I have to say about that. Want a chocolate?
"Beware the Jabberwock, my son!
The jaws that bite, the claws that catch!
Beware the Jubjub bird, and shun
The frumious Bandersnatch!"