alpine linux installer: bump to 3.18.3

alpine-install-on-disk.sh

@@ -5,6 +5,7 @@ if [ $# -ne 3 ]; then
     echo "   disk: which disk to install to"
     echo "   ssh-keyfile: ssh keys to add into the image"
     echo "   use efi or bios partitioning"
+    echo "post install in OS: apk add hdparm sudo wget efibootmgr git"
     exit 1
 fi
 
@@ -15,7 +16,7 @@ DISK=$1; shift
 SSH_KEYS=$1; shift
 BOOT_VIA=$1; shift
 
-MAJOR_VERSION=3.17
+MAJOR_VERSION=3.18
 MINOR_VERSION=3
 IMAGE=alpine-minirootfs-$MAJOR_VERSION.$MINOR_VERSION-x86_64.tar.gz