Fix stale docs: grub cmdline now has resume params, swapfile back for hibernation

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ZRAM.md

@@ -6,18 +6,19 @@ in RAM. That suits this machine: 15GiB RAM, and neon's root lives on a
 slow microSD card in the built-in slot (`sda`) that you don't want to swap to or wear
 out.
 
-## Current state (2026-09-27)
+## Current state (2026-09-28)
 
 ```
-$ zramctl
-NAME       ALGORITHM DISKSIZE DATA COMPR TOTAL STREAMS MOUNTPOINT
-/dev/zram0 zstd            8G   4K   59B   20K         [SWAP]
 $ swapon --show
-NAME       TYPE      SIZE USED PRIO
-/dev/zram0 partition   8G   0B  100
+NAME       TYPE      SIZE   USED PRIO
+/dev/zram0 partition   8G 582.5M  100
+/swapfile  file       16G     0B   10
 ```
 
-The zram device is the only swap. zswap is off
+zram (priority 100) takes all everyday swapping. The 16GB `/swapfile`
+(priority 10) is there for the hibernation image (see
+"Suspend-then-hibernate" in `NEON-CUSTOMIZATIONS.md`). It only gets
+ordinary swap pages if zram fills up. zswap is off
 (`/sys/module/zswap/parameters/enabled` = `N`), and there's nothing
 zram-related on the kernel command line.
 
@@ -82,8 +83,8 @@ SIZE=8192
 PRIORITY=100
 EOF
 sudo systemctl enable --now zramswap
-# comment out any /swapfile line in /etc/fstab, then:
-sudo swapoff /swapfile
+# drop any old swapfile from /etc/fstab (a hibernation swapfile is set
+# up separately, see NEON-CUSTOMIZATIONS.md)
 # persist swappiness
 echo 'vm.swappiness=100' | sudo tee /etc/sysctl.d/99-zram.conf && sudo sysctl --system
 ```