docs: fix two review findings from the reorg audit

An adversarial review of the reorg surfaced two doc inaccuracies:

- timers.md: a `time` code example still did `@import("runtime").time`, which
  no longer compiles — the runtime aggregator was deleted. Now `@import("time")`.
  (Reorg regression: the sweep rewrote `runtime.x` member access but not the
  `@import("runtime")` form inside a fenced code block.)

- sysv.md: `callconv(system.kernel_abi)` named a non-existent `system` module;
  `kernel_abi` lives in the boot-handoff contract (system/boot-handoff.zig),
  imported as `boot_handoff`. Now `boot_handoff.kernel_abi`. (Pre-existing bug —
  "system" was the file-path prefix mistaken for a module namespace — found and
  fixed opportunistically.)

docs/sysv.md

@@ -59,9 +59,9 @@ danos's two binaries default to different conventions:
 When the loader jumps to the kernel passing the `BootInformation` pointer, both sides have
 to agree *which register that pointer lands in*. Left to their defaults, the loader
 would place it in RCX while the kernel looked in RDI — and the kernel would read
-garbage. So both sides reference the same `system.kernel_abi` (SysV): the loader's
+garbage. So both sides reference the same `boot_handoff.kernel_abi` (SysV): the loader's
 function-pointer type and the kernel's `_start` both carry
-`callconv(system.kernel_abi)`, and the pointer reliably arrives in RDI. That is the
+`callconv(boot_handoff.kernel_abi)`, and the pointer reliably arrives in RDI. That is the
 whole reason `kernel_abi` lives in the shared contract — see [efi.md](efi.md) for
 the handoff it governs.