This times a million. Microsoft, OpenBSD and Golang are the only things I've found that produce good quality extensive reference documentation these days that I can take offline.
Python documentation, while extensive, is crappy.
I still miss my Sun Ultra enterprise 2. That was documented to bits.
To add to your list I like the PostgreSQL manuals. They always seem detailed and clear.
I find the Rails documentation awful lacking a lot of detail with an expectation that you read the source which in places is fairly hard to follow through several layers and even if you find the relevant part without good documentation you can't tell if it is a bug or intended behaviour in some cases.
Python documentation, while extensive, is crappy.
I still miss my Sun Ultra enterprise 2. That was documented to bits.