Github uses different syntax to render README.md and its wiki pages, for
no obvious reason.

Change-Id: I8905bf6ad7a72e6e1bfb3beb83f522ca5956128b
Reviewed-on: http://gerrit.cloudera.org:8080/272


Reviewed-by: Alex Leblang <alex.leblang@cloudera.com>
Tested-by: Henry Robinson <henry@cloudera.com>