README: Update to reflect what Poky is today

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

README

@@ -1,10 +1,25 @@
-OpenEmbedded-Core
-=================
+Poky
+====
 
-For information about OpenEmbedded see their website:
-    http://www.openembedded.org/
+Poky is an integration of various components to form a complete prepackaged
+build system and development environment. It features support for building
+customised embedded device style images. There are reference demo images
+featuring a X11/Matchbox/GTK themed UI called Sato. The system supports
+cross-architecture application development using QEMU emulation and a
+standalone toolchain and SDK with IDE integration.
+
+Additional information on the specifics of hardware that Poky supports
+is available in README.hardware. Further hardware support can easily be added
+in the form of layers which extend the systems capabilities in a modular way.
+
+As an integration layer Poky consists of several upstream projects such as 
+BitBake, OpenEmbedded-Core, Yocto documentation and various sources of information 
+e.g. for the hardware support. Poky is in turn a component of the Yocto Project.
 
-The Yocto Project has extensive documentation about OE including a reference manual
-which can be found at:
+The Yocto Project has extensive documentation about the system including a 
+reference manual which can be found at:
     http://yoctoproject.org/community/documentation
 
+For information about OpenEmbedded see their website:
+    http://www.openembedded.org/
+