I like writing documentation for processes at work. I always aim it at the “I’m familiar with the tools but haven’t done this before” person. I always include examples of the actual commands because it is one thing to describe a command but when you see it it makes FAR more sense.

Any of the classic RFCs. I really like the way RFCs are written.

Also, they’re extremely verbose, but the Intel x86 processor manuals are fascinating

Is this loss?

I loved when games came with manuals. FI Sid Meiers Pirates

Aviation procedures manuals.

You more remember documentation which sucks than a good examples.
Sometimes is better to just read a source code.