chore(guide): add corrections and updates to the install guide

INSTALLATION.md

@@ -2,8 +2,13 @@
 
 - The installations presented in this repository are always luks encrypted
 - For simplicity I'm using device labels rather than uuids
+- Secure Boot has to be disabled in the firmware, the installer iso isn't signed
 
-1. the partitioning layout should look somewhat like this after the installation
+1. create the partitions with `cfdisk` or `fdisk` (gpt)
+   - `nvme0n1p1`: 2G, type `EFI System`, otherwise the firmware won't find the bootloader
+   - `nvme0n1p2`: the rest, type `Linux filesystem`
+
+   the layout should look somewhat like this after the installation
 ```bash
 NAME               MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINTS
 nvme0n1            259:0    0 476.9G  0 disk
@@ -30,12 +35,13 @@ cryptsetup luksOpen /dev/nvme0n1p2 cryptroot
 pvcreate /dev/mapper/cryptroot
 # create a volume group inside
 vgcreate lvmroot /dev/mapper/cryptroot
-# create the swap volume
-lvcreate --size 8G lvmroot --name swap
+# create the swap volume, half the ram (no hibernation)
+lvcreate --size 16G lvmroot --name swap
 # if you desire, create a home volume
 lvcreate --size 150G lvmroot --name home
-# create the root volume
-lvcreate -l 100%FREE lvmroot --name root
+# create the root volume, leave some space in the vg to grow volumes later
+# (lvextend -r -L +50G lvmroot/home works while mounted)
+lvcreate -l 90%FREE lvmroot --name root
 
 # format as usual for root partition
 mkfs.ext4 -L "nixroot" /dev/mapper/lvmroot-root
@@ -47,7 +53,7 @@ mkswap -L "nixswap" /dev/mapper/lvmroot-swap
 # mount root
 mount /dev/disk/by-label/nixroot /mnt
 # mount boot
-mount --mkdir /dev/nvme0n1p1 /mnt/boot
+mount --mkdir /dev/disk/by-label/nixboot /mnt/boot
 # again, if you did the home volume
 mount --mkdir /dev/disk/by-label/nixhome /mnt/home
 # turn on swap
@@ -59,8 +65,7 @@ swapon /dev/disk/by-label/nixswap
 # generate templates and update the hardware-configuration.nix
 nixos-generate-config --root /mnt
 
-# add dm-crypt and dm-mod to the kernelModules
-boot.initrd.kernelModules = [ "dm-crypt" "dm-mod" ];
+# no extra kernelModules needed, luks and lvm load dm_crypt and dm_mod themselves
 
 # add file systems using labels
 fileSystems."/" =
@@ -81,7 +86,13 @@ swapDevices =
   ];
 
 # point the bootloader to the luks device
-boot.initrd.luks.devices."cryptroot".device = "/dev/disk/by-label/nixcrypt";
+boot.initrd.luks.devices."cryptroot" = {
+  device = "/dev/disk/by-label/nixcrypt";
+  # without this fstrim never reaches the ssd
+  allowDiscards = true;
+  # lower latency on nvme
+  bypassWorkqueues = true;
+};
 ```
 
 4. install nixos