Update half_inch_open_reel.md
Update half_inch_open_reel.md

The Museum of Obsolete Media page linked here before (Sony EV 1-inch open reel video tape) is a rare 1" format (not type A, B, or C) that is more like 1/2" formats than the other 1"es!
bavc/avaa,bavc/avaa,bavc/avaa