Why did they put installation script in INSTALL INSTEAD OF install.sh?
Most other repositories i have seen put human-readable instructions in there.
The interesting part is the two references to a person who has long since passed, Uriel. The make file and configure files both print "read the README file." I am sure he complained that most people would blindly unpack the source and immediately run make or configure without ever reading anything. It could be a way to force people to RTFM. But that is just my opinion. If you really want an answer, drop an email to the 9fans mailing list and ask. It's still active.
IBM systems have the famous Red Books, but ok it isn't included.
Windows before the Internet days, when the SDK came in CD, having a MSDN subscription meant receiving a box with all documentation from Microsoft.
Inferno as Plan 9's successor also included all documentation.
Niklaus Wirth OSes for Modula-2 and Oberon, had the OS documentation as hypertext.
All Xerox PARC OSes, across Smalltalk, Interlisp-D and Mesa/Cedar had online help with the system documentation.
Also, this project is designed for operating systems other than Plan 9.
I despair at your (and GGP) lack of comprehension
It's a port of a collection of plan 9 userspace to a non-9 operating system.
Perhaps you've now learnt something
GG