Code is not documentation - and in my experience it is usually pretty unreadable anyway, being written in a crap language like C I expect. I do not understand how people expect systems to be interoperable if the protocols used are not well documented - or is that why I so often hear about "weird problems" and things not quite working right? Someone tried back in 2015, presumably when making a start. Shame it wasn't maintained unless I am just not finding it.
I am getting too old for this. When I started programming the ASCII text of the documentation would be bigger than the code itself!!