Update mixer concept page

- Update concept page to include a comparative overview of mixer and mixin
- Added images to illustrated differences between mixer and mixin
- Add related links
- Corrected label for deploy-at-scale.rst so that it could be linked from mixer concept page

Signed-off-by: Kristal Dale <kristal.dale@intel.com>

source/clear-linux/concepts/mixer-about.rst

@@ -3,21 +3,83 @@
 Mixer
 #####
 
-Mixing refers to composing a custom, versioned image of |CL-ATTR| for a
-specific use case. While upstream |CL| provides options to install bundles
-for various capabilities, some developers and OSVs may wish to either
-augment the operating system with functionality from their own packages
-or modify the structure of current bundles. Mixing offers a method to add
-capabilities while retaining the ability to stay up to date with an upstream
-version of |CL|.
+|CL-ATTR| is a powerful, modular, and customizable OS. Upstream |CL| offers
+many images for different deployment environments and use-cases.  There are
+hundreds of bundles that will meet most, if not all, of your OS and software
+needs.
 
-Mixing is a multi-step process that starts with installing the mixer bundle
-using swupd. You will also need a working knowledge of
-:abbr:`RPMs (RPM Package Manager files)` and how |CL| bundles work. For a
-detailed guide on how to create a |CL| mix, visit :ref:`mixer`.
+However, if you need additional customization or content, |CL| provides the
+mixer tool to customize the OS. With mixer, there are two approaches to
+customization:
+
+* :ref:`create-mix`
+* :ref:`create-mixin`
+
+Which approach you choose will depend on the level of customization that you
+need.
+
+.. _create-mix:
+
+Create a mix
+============
+
+The first approach is to use the mixer tool to create a derivative of the |CL|
+that contains your custom software. This is known as creating a mix. In your
+mix, you can
+
+* Use any existing upstream bundles with no modification.
+* Redefine what goes into existing bundles.
+* Create completely new, custom bundles with your own custom packages.
+
+With mixer you are not required to incorporate every upstream release into your
+mix. You decide which upstream versions to update your derivative to, as
+illustrated in Figure 1.
+
+.. figure:: figures/mixer-about-1.png
+   :scale: 75%
+   :alt: Creating a custom mix.
+
+   Figure 1: With a custom mix, you add your custom bundle and decide which
+   upstream versions to update your mix to, on your own release cycle.
+
+Creating your own mix forks away from the |CL| upstream and requires that you
+act as your own OSV. There is a greater level of responsibility, requiring
+more infrastructure and processes to adopt. However, with this approach, you
+have a higher degree of control and customization of your custom |CL|.
+
+
+.. _create-mixin:
+
+Create a mixin
+==============
+
+The second approach is to use the mixin tool, a light wrapper for mixer, to
+create custom bundles and sideload them into your upstream version of |CL|.
+This is known as a mixin. A mixin is useful when you need to add custom or 3rd
+party content but want to keep on the upstream update cycle, as shown in
+Figure 2. You can also create new bundles using upstream packages.
+
+.. figure:: figures/mixer-about-2.png
+   :scale: 75%
+   :alt: Creating a custom mix.
+
+   Figure 2: With a mixin you can add custom bundles, but stay on upstream.
+
+Mixin is primarily intended for end users. It is easier to adopt as it does
+not require breaking from upstream or acting as an OSV. With mixin
+
+* You are responsible for maintaining and testing your custom bundle(s).
+* You retain access to all upstream bundles and updates.
+* You can easily revert your system back to the upstream version.
 
 Related topics
 ==============
 
-* :ref:`swupd-about`
+|CL| provides flexibility in how you customize your OS. Learn more about mixer
+and related topics to decide which customization approach is best for you.
+
+* :ref:`mixer`
+* :ref:`mixin`
 * :ref:`bundles-about`
+* :ref:`swupd-about`
+* :ref:`deploy-at-scale`

source/clear-linux/guides/deploy-at-scale.rst

@@ -1,4 +1,4 @@
-.. _deploy-at-scale.rst:
+.. _deploy-at-scale:
 
 Deploy at Scale
 ###############