add release notes document, plus copyedits to readme

Change-Id: Icb308dfeed57478a1744be8f56f6e2ba6f797249
diff --git a/ReadMe.md b/ReadMe.md
index e6303af..834d746 100644
--- a/ReadMe.md
+++ b/ReadMe.md
@@ -1,10 +1,15 @@
 # What is Mendel Linux?
 
 Mendel Linux is a lightweight derivative of Debian Linux that runs on a number
-of Coral development boards, including the Coral EdgeTPU.
+of Coral development boards, such as the
+[Dev Board](https://coral.ai/products/dev-board/) and
+[SoM](https://coral.ai/products/som/).
 
 If you're looking to get started with any of the Coral boards, please take a
-look at the [Coral Website](https://coral.withgoogle.com) for more information.
+look at the [Coral doccumentation](https://coral.ai/docs) for more information.
+
+If you want to know what's changed in Mendel, see our
+[release notes](https://coral.googlesource.com/docs/+/refs/heads/master/Releases.md).
 
 If you're looking to get started developing, patching, or building Mendel for
 your own uses, please read our [Getting Started
@@ -34,16 +39,18 @@
 To build an image from our tooling for one of our boards, check out [Getting
 Started
 documentation](https://coral.googlesource.com/docs/+/refs/heads/master/GettingStarted.md)
+
 Note: we generally discourage this, as we put a great deal of effort into making
 sure our releases run well on the boards we target. Mendel is a proper Linux
 distribution: we work with packages, not images, and any image should be
 possible to upgrade to the latest release with a simple `apt-get dist-upgrade`
-without requiring a reboot (modulo kernel and bootloader updates, obviously).
+without requiring a reboot (modulo kernel and bootloader updates, obviously,
+which require [reflashing the board](https://coral.ai/docs/dev-board/reflash/)).
 
 ## What do we support?
 
-Mendel currently only supports the Coral EdgeTPU Dev Board (also known as
-enterprise, or phanbell).
+Mendel currently only supports the Coral Dev Board (also known as
+enterprise, or phanbell) and SoM.
 
 For development, our build system only currently supports Linux systems.
 Unfortunately, this is due to various factors out of our control, so it is
diff --git a/Releases.md b/Releases.md
new file mode 100644
index 0000000..9428b75
--- /dev/null
+++ b/Releases.md
@@ -0,0 +1,41 @@
+# Mendel release notes
+
+This is a non-exhaustive summary of changes included in each version of Mendel.
+
+For system image downloads, see [coral.ai/software](https://coral.ai/software/).
+
+
+## 4.0 (day)
+
++   First release based on [Debian 10 (buster)](
+    https://www.debian.org/releases/buster/arm64/release-notes/ch-whats-new.en.html)
+    (Note that our distribution does not include everything from Debian;
+     for example, Mendel does not include desktop environments and applications,
+     because our system is designed for embedded systems. Also, the
+     new SecureBoot and AppArmor changes do not apply to Mendel)
++   Support for Python 3.7
++   Support for OpenCV and OpenCL
++   Upgraded GStreamer pipelines
++   Improved stability for memory timing
++   Upgraded Linux Kernel (4.14)
++   Upgraded U-Boot bootloader (2017.03.3)
+
+
+## 3.0 (chef)
+
++   First open source release
++   First release with the Mendel Development Tool (MDT)
++   Improved security for SSH authentication
+
+
+## 2.0 (beaker)
+
++   Resolved Hynix/Micron memory timing stability
++   Support for USB-C connections in U-Boot
++   Support for Mac in flash.sh script
++   Released edgetpu_demo for out-of-box Edge TPU demo
+
+
+## 1.0 (alpha)
+
+Our first Mendel release!
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