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/venomoth.asm

@@ -0,0 +1,10 @@
+; VenomothPokedexEntry: ; 0x182abf
+	db "POISONMOTH@" ; species name
+	dw 411, 280 ; height, weight
+
+	db   "The scales it"
+	next "scatters will"
+	next "paralyze anyone"
+	page "who touches them,"
+	next "making that person"
+	next "unable to stand.@"