Add README about broken redirects

README.rst

@@ -0,0 +1,7 @@
+Please update your edx-platform URLs
+####################################
+
+This repository is no longer in use -- use https://github.com/openedx/edx-platform instead (in the openedx org).
+
+For more information about this move and why you're seeing this instead of being redirected, see:
+https://discuss.openedx.org/t/please-update-your-edx-platform-git-url/12387