FYI: update to "terms of service" description for this site

I have added a paragraph (cleared by Fedora Legal) to the terms of service page for this site. This paragraph reads:

Community moderators, forum leaders, and site administrators are here to help keep the discussion positive, constructive, and on-topic. They may choose to move, hide, edit, or delete posts in service of this goal, even if that post does not necessarily rise to the level of a Code of Conduct violation. If you see a post which may need moderator attention, please do not hesitate to flag it. If you notice something which may violate the Code of Conduct, please file a report in the Fedora Project Code of Conduct issue tracker.

This is not a new policy but rather reflects existing practices and usage, including the fact that the Discourse software is built to allow and encourage community-based moderation.