fix: replace broken docs/STATUS.md cross-reference

The build_grub2_204.sh header comment referenced a docs/STATUS.md
file that doesn't exist (a TODO left over from an earlier session).
Replace the broken reference with a pointer to the actual architecture
documentation in INTERFACES.sh (the Build Architecture section that
was added in the previous commit).

scripts/build_grub2_204.sh

@@ -9,8 +9,10 @@
 #
 # The hiperiso source tree in `src/grub2/` is retained for reference but
 # intentionally NOT compiled in here — it's an unfinished rebrand attempt
-# that's blocked on partial modsrc/sed mismatches. See `docs/STATUS.md`
-# (TODO) for the longer-term rebrand plan.
+# that's blocked on partial modsrc/sed mismatches. The substrate approach
+# is the supported path; the historical rebrand sources are kept only
+# for context. See INTERFACES.sh (Build Architecture section) for the
+# full rationale.
 #
 # Usage: scripts/build_grub2_204.sh
 # Output: grub2/bin/BOOTX64.EFI, grub2/bin/grubx64_real.efi, grub2/bin/grubx64.efi