README: Rename to README.OE-Core so its clear where its from/belongs/is about

This means we can add it to poky and reduce delta/confusion between the
contents.

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

README.OE-Core

@@ -0,0 +1,29 @@
+OpenEmbedded-Core
+=================
+
+OpenEmbedded-Core is a layer containing the core metadata for current versions
+of OpenEmbedded. It is distro-less (can build a functional image with
+DISTRO = "nodistro") and contains only emulated machine support.
+
+For information about OpenEmbedded, see the OpenEmbedded website:
+    http://www.openembedded.org/
+
+The Yocto Project has extensive documentation about OE including a reference manual
+which can be found at:
+    http://yoctoproject.org/documentation
+
+
+Contributing
+------------
+
+Please refer to
+http://www.openembedded.org/wiki/How_to_submit_a_patch_to_OpenEmbedded
+for guidelines on how to submit patches.
+
+Mailing list:
+
+    http://lists.openembedded.org/mailman/listinfo/openembedded-core
+
+Source code:
+
+    http://git.openembedded.org/openembedded-core/