Journalists on the culture beat often get to be on hand for big events. Usually they can see them coming. As Season 2 of the Welsh football series “Welcome to Wrexham” rolls out on FX, the Monitor’s Stephen Humphries relives a May assignment that dropped him into the stadium where a low-tier team would notch an improbable victory. He tells guest host Kendra Nordin Beato about the surge of fan identity that the team’s win gave to its sleepy hometown – and to a larger community beyond.