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/unown.asm

@@ -0,0 +1,10 @@
+; UnownPokedexEntry: ; 0x1d0373
+	db "SYMBOL@" ; species name
+	dw 108, 110 ; height, weight
+
+	db   "Because different"
+	next "types of UNOWN"
+	next "exist, it is said"
+	page "that they must"
+	next "have a variety of"
+	next "abilities.@"