Add some comments to test_ddl_deparse and a README

Alvaro Herrera <alvherre@alvh.no-ip.org>

Commit: f1f3434f210450af2e3dab08fbc05a9edd0b67a4
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: 2015-07-20T09:20:40Z
Releases: 9.5.0
Add some comments to test_ddl_deparse and a README

Per comments from Heikki Linnakangas.

Backpatch to 9.5, where this module was introduced.

Files