[ticket/12197] Fix several misleading FAQ entries

https://tracker.phpbb.com/browse/PHPBB3-12197
<prototech> nickvergessen, changing to moderator makes the statement that follows incorrect since moderators have no such power https://github.com/phpbb/phpbb/pull/2656/files#diff-f6395046fea938f10ae82f00efc802ddR257