fix: read each europe-only region tag in its code

Region tags must name the territory the code selects a file for. Each
entry tagged europe alone was read at its pin: PAL branches Australian
media reach now include oceania, and tags that follow a video standard,
a user setting or a hardcoded value are removed.

emulators/kronos.yml

@@ -158,8 +158,8 @@ files:
   - name: "epr-17954a.ic8"
     archive: stvbios.zip
     system: sega-stv
-    region: [europe]
     required: false
+    note: "Picked by the kronos_stv_favorite_region option, Europe by default, among the BIOS regions the set accepts (yabause/src/ctrl/src/stv.c:2435, 2562-2564)."
     size: 524288
     crc32: "f7722da3"
     validation: [crc32]