add rule to generate <set code>.txt from mtgjson.com/json/<set code>.json

Makefile

@@ -801,6 +801,9 @@ push: clean normalize_files checks debug
 resources/magic/data/AllCardNames.txt:
 	grep "<name>" -r cards/cards.xml | sed 's/<[^>]*>//g;s/^ *//' | unaccent utf-8 | recode html..ascii | sort > $@
 
+resources/magic/data/sets/%.txt:
+	curl https://mtgjson.com/json/$*.json | jq -r .cards[].name | LC_ALL=C sort | uniq > $@
+
 missing_override:
 	grep public -B1 -r release/Magarena/scripts | awk '/Override/ {skip = NR + 1} NR != skip {print $$0}' | grep -v Override | grep release > $@