meta-agl-demo: new file for "meta-agl-demo" topic.

This is the re-write for the new "AGL Layers" section in
"Developer Guides".  The new file is a rewrite of the existing
README.md file.

Change-Id: I04faa67966194465797f8b8433d72f3122a8eb28
Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>

diff --git a/meta-agl-demo.md b/meta-agl-demo.md
new file mode 100755 (executable)
index 0000000..8dd9d99
--- /dev/null
+++ b/meta-agl-demo.md
@@ -0,0 +1,175 @@
+## Introduction
+
+The `meta-agl-demo` layer is the IVI demo layer that uses the core 
+AGL infrastructure provided through profiles.
+The layer sits on top of the profiles as follows:
+
+profile-core <- profile-gfx <- profile-gfx-qt5
+
+The layer provides a reference platform and applications.
+The BitBake target name for the demo platform is `agl-demo-platform`,
+which is the full demo platform image.
+
+## Layer Dependencies
+
+This section describes dependencies for the `meta-agl-demo` layer.
+Dependencies are grouped into base, hardware, and feature dependencies.
+
+### Base Dependencies
+
+The `meta-agl-demo` layer has the following base dependencies:
+
+* Yocto Project Release:
+
+  - URI: git://git.yoctoproject.org/poky
+  - Branch: "thud"
+  - Tested Revision: See the [`default.xml`](https://github.com/leon-anavi/AGL-repo/blob/master/default.xml)
+    manifest file for the `AGL-repo` repository for revision
+    information.
+
+* AGL `meta-agl` Layer:
+
+  - URI: https://gerrit.automotivelinux.org/gerrit/AGL/meta-agl
+  - Branch: "flounder"
+
+* OpenEmbedded `meta-openembedded` Layer:
+
+  - Branch: "thud"
+  - Tested Revision: See the [`default.xml`](https://github.com/leon-anavi/AGL-repo/blob/master/default.xml)
+    manifest file for the `AGL-repo` repository for revision
+    information.
+
+  Specifically, out of `meta-openembedded`, these sub-layers are used:
+
+  - `meta-oe`
+  - `meta-multimedia`
+  - `meta-efl`
+  - `meta-networking`
+  - `meta-python`
+  - `meta-ruby`
+
+* Yocto Project `meta-qt5` Layer from the 
+  [OpenEmbedded Layer Index](https://layers.openembedded.org/layerindex/branch/master/layers/):
+
+  - URI: https://github.com/meta-qt5/meta-qt5.git
+  - Branch:   "thud"
+  - Tested Revision: See the [`default.xml`](https://github.com/leon-anavi/AGL-repo/blob/master/default.xml)
+    manifest file for the `AGL-repo` repository for revision
+    information.
+
+### Feature Dependencies
+
+The `meta-agl-demo` layer has the following AGL
+[feature](../../../../getting_started/en/dev/reference/image-workflow-initialize-build-environment.html#agl-features)
+dependencies:
+
+**The `agl-appfw-smack` Feature:**
+
+<!--
+* Yocto Project `meta-intel-iot-security` Layer from the OpenEmbedded Layer Index:
+
+  - URI: https://github.com/01org/meta-intel-iot-security
+  - Branch: "thud"
+  - Tested Revision: See the [`default.xml`](https://github.com/leon-anavi/AGL-repo/blob/master/default.xml)
+    manifest file for the `AGL-repo` repository for revision
+    information.
+-->
+
+* Yocto Project `meta-security` Layer:
+
+  - URI: https://git.yoctoproject.org/cgit/cgit.cgi/meta-security
+  - Branch: "master"
+  - Tested Revision: See the [`default.xml`](https://github.com/leon-anavi/AGL-repo/blob/master/default.xml)
+    manifest file for the `AGL-repo` repository for revision
+    information.
+
+* AGL's `meta-app-framework` Layer Within the `meta-agl-extra` Layer:
+
+  - URI: https://gerrit.automotivelinux.org/gerrit/gitweb?p=AGL/meta-agl-extra.git
+  - Branch: "master"
+
+**The `agl-sota` Feature:**
+
+* AGL's `meta-sota` Layer Within the `meta-agl-extra` Layer:
+
+  - URI: https://gerrit.automotivelinux.org/gerrit/gitweb?p=AGL/meta-agl-extra.git
+  - Branch: "master"
+
+* OpenEmbedded's `meta-openembedded` Layer:
+
+  - URI: https://github.com/openembedded/meta-openembedded
+  - Branch: "thud"
+  - Tested Revision: See the [`default.xml`](https://github.com/leon-anavi/AGL-repo/blob/master/default.xml)
+    manifest file for the `AGL-repo` repository for revision
+    information.
+
+    In particular, the `meta-openembedded` layer depends on the following
+    sub-layers:
+
+      - `meta-filesystems`
+      - `meta-ruby`
+
+<!--
+* OpenEmbedded's `meta-rust` Layer:
+
+  - URI: https://github.com/meta-rust/meta-rust
+  - Branch: "thud"
+  - Tested Revision: See the `[default.xml](https://github.com/leon-anavi/AGL-repo/blob/master/default.xml)`
+    manifest file for the `AGL-repo` repository for revision
+    information.
+-->
+
+**The `agl-netboot` Feature:**
+
+* AGL's `meta-netboot` Layer Within the `meta-agl` Layer:
+
+  - URI: https://gerrit.automotivelinux.org/gerrit/gitweb?p=AGL/meta-agl.git
+  - Branch: "master"
+
+
+## Packagegroups
+
+AGL DEMO Platform's 
+[packagegroups](https://www.yoctoproject.org/docs/2.4.4/dev-manual/dev-manual.html#usingpoky-extend-customimage-customtasks)
+consist of the following:
+
+### packagegroup-agl-demo-platform
+
+This packagegroup is used for generating the `agl-demo-platform` image,
+which is the full image for the AGL distributions IVI profile.
+You can see the recipe (i.e. `agl-demo-platform.bb`) that installs 
+the `packagegroup-agl-demo-platform` packagegroup
+[here](https://git.automotivelinux.org/AGL/meta-agl-demo/tree/recipes-platform/images/agl-demo-platform.bb).
+
+As meta-agl's design of packagegroups, the `agl-demo-platform.bb` recipe installs
+the `packagegroup-agl-demo-platform` packagegroup, which pulls in the following
+packages of the DEMO applications:
+
+  * `agl-demo-platform`
+  * `packagegroup-agl-image-minimal`
+  * `packagegroup-agl-image-ivi`
+  * `packagegroup-ivi-common-core`
+  * `packagegroup-agl-demo-platform`
+
+<!--
+### packagegroup-agl-appfw*
+
+These packagegroups contain packages for the AGL distribution's
+Application Framework.
+Subsystem should maintain `packagegroup-agl-appfw-[subsystem].bb`, which
+should hold sufficient packages for the Application Framework.
+
+Subsystems also can maintain their own packagegroups using appropriate
+`recipes-*/`.
+For example, Qt5 has two packagegroups in `meta-agl-demo`:
+`packagegroup-agl-appfw-native-qt5` and `packagegroup-agl-demo-qt-examples`,
+which are under `recipes-qt/`.
+
+The `packagegroup-agl-appfw-native-qt5` is included by
+`packagegroup-agl-appfw-native` because Qt5 belongs to native application
+framework of AGL Distro.
+
+Because the `packagegroup-agl-demo-qt-examples` is not mandatory for
+the AGL Application Framework and the AGL DEMO, the packagegroup is added
+to the layer's `local.conf` file only when needed.
+-->