Github user interface tip for the unwary.

0_AVOID_GITHUB_ZIP_FILES/README.md

@@ -0,0 +1,17 @@
+Github "Download ZIP" button is not supported
+=============================================
+Please use git clone instead.
+
+The "Download ZIP" button on Github has two problems:
+
+1. The archive does not contain Git metadata (.git directory) which
+   is needed by OVIS when figuring out the version hashes and submodules.
+
+2. It does not contain submodule sources.
+
+Others have asked GitHub for a way to disable the zip portion of this 
+button without result.  (see also project rose-compiler/rose for details.)
+
+This README lives in a directory whose name causes it to appear
+as close as possible to the "Download ZIP" button in the GitHub web
+interface.