Minor fix on forums plugin for localization

Hi, thanks for the great plugin.
In order to full localize a small change in forums.php line 1448
Replace
$content = $content . '<th scope="row">' . __('Post:') . '</th>';
with
$content = $content . '<th scope="row">' . __('Post:','wpmudev_forums' ) . '</th>';

Please let the developer know in order to include this in the next version.

Cheers Lena