docs: README, plan, guides and the site describe what is built now

README: rewritten around what runs (Linux software, Xorg, apk, Linux's drivers), the honest gaps, measured numbers.
plan/: 1.0.md is the finish line, where each clause of the acceptance test stands, and the register (one failing
clause: a root that survives a reboot); built plans (foundations, hybrid, alpine, xorg) and the decided-against one
(wayland) are gone, their content lives in architecture/; roadmap.md is only what is still open.
guides: building/layout/testing/adding-a-driver (Linux code may be used). history: four entries (ls -lR, TLB
shootdowns, MDIO 0x02460246, netlink MSG_TRUNC). Website: cards, stack, download page, docs index.
Code comments that pointed at deleted plan docs point at the architecture docs.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EVRhxi9zpdW2uDUN4FVcao

include/dev/pciuser.h

@@ -2,7 +2,7 @@
 //
 // /dev/pci -- device access from userspace.
 //
-// docs/plan/hybrid.md, mechanisms 2 and 4: MMIO and DMA to a process. This is
+// docs/architecture/devices.md, mechanisms 2 and 4: MMIO and DMA to a process. This is
 // the interface a driver that does not live in the kernel talks to, and it is
 // deliberately about *PCI devices*, not about any particular driver model.
 //
@@ -23,7 +23,7 @@
 //
 // There is no IOMMU. A process holding a DMA buffer can point the device at
 // any physical address, so this isolates a driver against its own *bugs* and
-// not against its own *intent*. docs/plan/hybrid.md says so at length and it
+// not against its own *intent*. docs/architecture/devices.md says so at length and it
 // remains true here: a crashed driver that restarts instead of taking the
 // machine down is the whole benefit, and it is not a security boundary.