add readme for packaging layout

packages/packaging-readme.md

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+## PrawnOS Packaging
+
+All programs, themes, etc that are not part of upstream debian are built as packages
+this allows PrawnOS the following benefits:
+- the PrawnOS apt repo is not a build dependency
+- test builds don't require any special steps-- just make the change locally and rebuild the filesystem
+- a user doesn't have to trust the PrawnOS apt repo to build their own image
+- the PrawnOS apt repo requires less bandwidth, as only package updates will be gotten from it
+
+Note that some packages that are available upstream, but only in unstable or testing repos or have
+fixes only in the unstable or testing repos are packaged as part of PrawnOS
+
+### Updating Packages
+By using packages for all parts of PrawnOS, updates are more straightforward. 
+When an existing PrawnOS install has out of date packages, the user can then either
+build the new version themselves or get the update from the repo using the standard "apt upgrade"
+
+### Package folder structure
+Packages are stored under component of the final PrawnOS image they belong to, and then for filesystem packages, the component of the filesystem they belong to. 
+Inside the package folder there are the following items:
+- `makefile`
+- source folder called `src`
+- a `.orig.tar.gz*` containing the package source.
+- a `.gitignore` to avoid commiting build artifacts, or unnecessary source files
+
+The contents of the `src` are the following:
+- a `debian` folder
+- the source files if the package is not packages upstream (by debian)
+- the patched source files if there are any PrawnOS specific patches. This is to keep the changes tracked by git. 
+
+If the source is from an upstream package, and no PrawnOS specific patches are carried then only the `debian` folder is in the `src` folder
+
+### Building packages
+Most packages are built in a host architecture agnostic fashion using pbuilder.
+The only notable exceptions to this are font packages, which are not architecture dependent and
+the kernel package, which handles cross compilation manually without a chroot. 
+
+To build any package, navigate to that packages folder and run
+```
+make clean
+make
+```
+the resulting .deb will be in that same folder when the build is complete
+
+### Uploading packages
+New packages, and package updates can upload to `deb.prawnos.com` by
+first building and then running
+```
+make upload
+```