Here is a list of all documented files with brief descriptions:

[detail level 1234567]

kernel
include
arch
x86
i386
gdt
gdt.h
idt
idt.h
io
io.h
mmu
paging.h
physicalmemorymanager.h
virtualmemorymanager.h
pic
pic.h
drivers
vga.h
kernel
tty
tty.h
libc
include
sys
cdefs.h
limits.h	Implementation-defined limit constants for freestanding environment
stdarg.h	Variable argument list macros
stdbool.h	Boolean type and constants
stddef.h	Common definitions for C programs
stdint.h	Fixed-width integer types
stdio.h
stdlib.h
string.h