Add a short note to indicate that this is not official one.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@20877 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/MailTemplates/readme.txt

 Mail Templates
 
+  Note: This is a Nexedi version of MailTemplates, but not the official
+  one.
+
   Mail Templates provide full access to Python's email package and
   allow the body of messages to be generated using Zope's Page
   Template technology. They work in both a Zope environment and a CMF