Mention non-MIT pot file licenses

[drnlm]

Several for the pot files under the i18n directory are marked as being LGPL v2 licensed, and, as far as I can see, many of the translators are not listed in the contributors file and so weren't part of the effort to relicense formencode.

This is not a major issue, but it would be good if this disparity is mentioned somewhere - either in the README or in the LICENSE file.