Change a few things

docs/how-the-build-process-works.md

@@ -0,0 +1,43 @@
+## How the build process works
+
+The following process is followed to build images:
+
+ * Iterate through all of the stage directories in alphanumeric order
+
+ * Bypass a stage directory if it contains a file called
+   "SKIP"
+
+ * Run the script `prerun.sh` which is generally just used to copy the build
+   directory between stages.
+
+ * In each stage directory iterate through each subdirectory and then run each of the
+   install scripts it contains, again in alphanumeric order. **These need to be named
+   with a two digit padded number at the beginning.**
+   There are a number of different files and directories which can be used to
+   control different parts of the build process:
+
+     - **00-run.sh** - A unix shell script. Needs to be made executable for it to run.
+
+     - **00-run-chroot.sh** - A unix shell script which will be run in the chroot
+       of the image build directory. Needs to be made executable for it to run.
+
+     - **00-debconf** - Contents of this file are passed to debconf-set-selections
+       to configure things like locale, etc.
+
+     - **00-packages** - A list of packages to install. Can have more than one, space
+       separated, per line.
+
+     - **00-packages-nr** - As 00-packages, except these will be installed using
+       the `--no-install-recommends -y` parameters to apt-get.
+
+     - **00-patches** - A directory containing patch files to be applied, using quilt.
+       If a file named 'EDIT' is present in the directory, the build process will
+       be interrupted with a bash session, allowing an opportunity to create/revise
+       the patches.
+
+  * If the stage directory contains files called "EXPORT_NOOBS" or "EXPORT_IMAGE" then
+    add this stage to a list of images to generate
+
+  * Generate the images for any stages that have specified them
+
+It is recommended to examine build.sh for finer details.