Rename all files in data/pokedex/entries/

Some people suggested this would be a good idea, and make management of
the files easier. I'm inclined to agree.

data/pokedex/entries/goldeen.asm

@@ -0,0 +1,10 @@
+; GoldeenPokedexEntry: ; 0x1b9626
+	db "GOLDFISH@" ; species name
+	dw 200, 330 ; height, weight
+
+	db   "During spawning"
+	next "season, they swim"
+	next "gracefully in the"
+	page "water, searching"
+	next "for their perfect"
+	next "mate.@"