Enchance documentations

I've been reading at the documentations recently (because sometimes I got bored :P) and tried to recall details of some of the issues I had. I added some that I think would be common for others.

More coming later if I could think of some else but I would like to get these merged first in case it might help.
It's really only a caveat for encrypting a non-encrypted chroot (also, not sure where "integration" came from).  I don't think we actually need the warning anymore, since there's code to handle when the conversion is halted.