Promote WOA 6

[vielmetti]

• [x] finish last-minute edits
• [x] internal slack
• [x] external slack
• [x] twitter
• [x] bcc list (a temporary expedient)
• [x] set up distro list on groups.io #12 in progress

[vielmetti]

skipping groups.io in favor of internal tools, in due time.