[Tweak] Ruleset Edition now required

[Shad]

Per the discussion here, PG-HQ now collects information about which ruleset you used to play your scenario. Available options are 3rd and 4th edition (shortly to be released).

While the dates of our earliest plays suggest that some of them probably were 2nd edition, I'm not interested in that data going forwards so everything prior to today has been automatically marked as 3rd edition.