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/pci.h

@@ -151,7 +151,7 @@ struct pci_driver {
     void (*attached)(struct pci_dev *, struct device *);
     // Give the device up, so a userspace driver can take it.
     //
-    // docs/plan/hybrid.md is built on the kernel *handing over* a device
+    // docs/architecture/devices.md is built on the kernel *handing over* a device
     // rather than a process wrestling it away: two drivers writing one set of
     // registers is not a subtle failure, it is hardware that appears to have
     // started lying. So the transfer is the incumbent's decision, and this is