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/ariados.asm

@@ -0,0 +1,10 @@
+; AriadosPokedexEntry: ; 0x1cd083
+	db "LONG LEG@" ; species name
+	dw 307, 740 ; height, weight
+
+	db   "Rather than mak-"
+	next "ing a nest in one"
+	next "specific spot, it"
+	page "wanders in search"
+	next "of food after"
+	next "darkness falls.@"