Update documentation

README

@@ -1,33 +1,41 @@
-This live CD is customized by roughly following the guidelines at:
-  https://help.ubuntu.com/community/LiveCDCustomization
-  https://help.ubuntu.com/community/LiveCDCustomizationFromScratch
-  https://help.ubuntu.com/community/MakeALiveCD/DVD/BootableFlashFromHarddiskInstall
-plus a lot of other info, like ubiquity and casper source code, and
-additions for making the resulting iso EFI bootable.
+Tools to customize an Ubuntu Live CD.  Many parts of this will end up
+being version-specific.  The host machine must be running systemd,
+since the image is executed inside a systemd-nspawn container.
 
-extractiso.sh
-  extract the original iso
+Set up host machine, which must be running a recent systemd:
 
-customize.sh
-  apply customizations
+  sudo apt-get install squashfs-tools xorriso isolinux systemd-container iptables
+  sudo systemctl start systemd-networkd
 
-enter.sh
-  chroot into the install (for optional manual customization)
+Choose a config:
 
-buildiso.sh
-  build the new iso
+  export BUILD_CONFIG=16.04
 
-run.sh -c
-  boot the iso in qemu with a blank hdd, to test the install
+Download and extract the original ISO:
 
-run.sh -d
-  boot the installed hdd in qemu
+  ./extractiso.sh
 
-cleanup.sh
-  remove everything but the isos
+Apply customizations, both to the outer ISO and the inner image.
+This will also run customizer-inner.sh inside a container:
 
+  ./customize.sh
 
-SHORT VERSION:
-  sudo apt-get install squashfs-tools xorriso isolinux systemd-container
-  time sudo sh -c "env BUILD_CONFIG=12.10 ./full-rebuild.sh"
-  time sudo sh -c "env BUILD_CONFIG=13.04 ./full-rebuild.sh"
+(Optional) Run and enter a shell in the container, for manual customization:
+
+  ./enter.sh
+
+Build the new ISO:
+
+  ./buildiso.sh
+
+Boot the ISO in QEMU with a blank HDD, to test and install:
+
+  ./run.sh -c
+
+Boot QEMU with the same HDD image as above, to test an "installed" system:
+
+  ./run.sh -d
+
+Remove everything but the ISOs:
+
+  ./cleanup.sh