Intro paras for Freezing and Packaging Your Code

I've tried to describe why you would choose one method over
another, and what the relative advantages and disadvantages
are of each method.

I'm painfully aware that I haven't covered the combo of
freezing an application *then* creating a Linux distro
package of it, but maybe that's a battle for another day.

My intent is to add more content on the Freezing page
once this commit is accepted, so I can hear your feedback
before doing any further work.

Thanks.

docs/shipping/packaging.rst

@@ -1,13 +1,43 @@
+.. _packaging-your-code-ref:
+
+===================
 Packaging Your Code
 ===================
 
-Packaging your code is important.
+Package your code to share it with other developers. For example
+to share a library for other developers to use in their application,
+or for development tools like 'py.test'.
 
-You'll need to package your code first before sharing it with other developers.
+An advantage of this method of distribution is its well established ecosystem
+of tools such as PyPI and pip, which make it easy for other developers to
+download and install your package either for casual experiments, or as part of
+large, professional systems.
+
+It is a well-established convention for Python code to be shared this way.
+If your code isn't packaged on PyPI, then it will be harder
+for other developers to find it, and to use it as part of their existing
+process. They will regard such projects with substantial suspicion of being
+either badly managed or abandoned.
+
+The downside of distributing code like this is that it relies on the
+recipient understanding how to install the required version of Python,
+and being able and willing to use tools such as pip to install your code's
+other dependencies. This is fine when distributing to other developers, but
+makes this method unsuitable for distributing applications to end-uers.
 
 The `Python Packaging Guide <https://python-packaging-user-guide.readthedocs.org/en/latest/>`_
 provides an extensive guide on creating and maintaining Python packages.
 
+Alternatives to Packaging
+:::::::::::::::::::::::::
+
+To distribute applications to end-users, you should
+:ref:`freeze your application <freezing-your-code-ref>`.
+
+On Linux, you may also want to consider
+:ref:`creating a Linux distro package <packaging-for-linux-distributions-ref>`
+(e.g. a .deb file for Debian or Ubuntu.)
+
 For Python Developers
 :::::::::::::::::::::
 
@@ -106,9 +136,42 @@ prerequisite for this is that you have an Amazon AWS account with an S3 bucket.
 
 * You can now install your package with :code:`pip install --index-url=http://your-s3-bucket/packages/simple/ YourPackage`
 
+.. _packaging-for-linux-distributions-ref:
+
 For Linux Distributions
 ::::::::::::::::::::::::
 
+Creating a Linux distro package is arguably the "right way" to distribute code
+on Linux.
+
+Because a distribution package doesn't include the Python interpreter, it
+makes the download and install about 2Mb smaller than
+:ref:`freezing your application <freezing-your-code-ref>`.
+
+Also, if a distribution releases a new security update for Python, then your
+application will automatically start using that new version of Python.
+
+However, creating and maintaining the different configurations required for
+each distribution's format (e.g. .deb for Debian/Ubuntu, .rpm for Red
+Hat/Fedora, etc) is a fair amount of work. If your code is an application that
+you plan to distribute on other platforms, then you'll also have to create and
+maintain the separate config required to freeze your application for Windows
+and OSX. It would be much less work to simply create and maintain a single
+config for one of the cross platform :ref:`freezing tools
+<freezing-your-code-ref>`, which will produce stand-alone executables for all
+distributions of Linux, as well as Windows and OSX.
+
+Creating a distribution package is also problematic if your code is for a
+version of Python that isn't currently supported by a distribution.
+Having to tell *some versions* of Ubuntu end-users that they need to add `the
+'dead-snakes' PPA <https://launchpad.net/~fkrull/+archive/ubuntu/deadsnakes>`_
+using `sudo apt-repository` commands before they can install your .deb file
+makes for an extremely hostile user experience. Not only that, but you'd have
+to maintain a custom equivalent of these instructions for every distribution,
+and worse, have your users read, understand, and act on them.
+
+Having said all that, here's how to do it:
+
 * `Fedora <https://fedoraproject.org/wiki/Packaging:Python>`_
 * `Debian and Ubuntu <http://www.debian.org/doc/packaging-manuals/python-policy/>`_
 * `Arch <https://wiki.archlinux.org/index.php/Python_Package_Guidelines>`_