added WARNING to make sure people read troubleshooting

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@39194 20353a03-c40f-0410-a6d1-a30d3c3de9de

buildout/README-2.12.txt

@@ -46,6 +46,9 @@ And run it:
 
   $ python2.6 -S bootstrap.py -c buildout-2.12.cfg
 
+WARNING: please read "Troubleshooting" section bellow, you may need to
+unset environment variables in your GNU/Linux distribution
+
 If curl or wget are available, it can be done in one line:
 
 in case of curl: