AGL Layers content: Added meta-agl.md and agl-layers-overview.md

These two files are based off the README.md and README-AGL.md
files.  I am pushing these two files so that they can undergo
a Gerrit review.  Questions exist in the form of
WRITER NOTES in the files.

Change-Id: Ie6d3355f0ff60e0362b720a298caf28aa5ac2045
Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/agl-layers-overview.md b/agl-layers-overview.md
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+Overview
+========
+
+The
+[AGL Project](https://www.automotivelinux.org/) is an automotive-specific
+development environment that provides a Linux distribution
+[AGL UCB](https://www.automotivelinux.org/software/unified-code-base).
+
+AGL uses layers designed to be compatible with the
+[Yocto Project](https://www.yoctoproject.org) and the
+[OpenEmbedded Project (OE)](https://www.openembedded.org/wiki/Main_Page).
+
+This section provides information about the layers used by the AGL Project:
+
+* **`meta-agl`**: Minimal set of software needed to create an AGL distribution
+  used to boot a system.
+  AGL profiles are built on top of this minimal set of software.
+
+* **`meta-agl-demo`**: Provides a reference or demo platform and applications
+  for the AGL Distribution.
+  The reference UI is part of the `meta-agl-demo` layer.
+
+* **`meta-agl-devel`**: Contains components under development or being tested.
+  This layer also contains software packages that OEMs need but do not exist
+  in AGL.