Added [in-progress] Developer Guides

Updated mkdocs.yml, README.md.
Text wrap markdowns at 80.

Bug-AGL: [SPEC-3633]

Signed-off-by: Shankho Boron Ghosh <shankhoghosh123@gmail.com>
Change-Id: I2d7b43cb870e97786d3eb101c60a2071cc50f0be
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/documentation/+/25498
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/docs/3_Developer_Guides/1_AGL_Layers/1_Overview.md b/docs/3_Developer_Guides/1_AGL_Layers/1_Overview.md
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+---
+title: Overview
+---
+
+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.