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/hitmontop.asm

@@ -0,0 +1,10 @@
+; HitmontopPokedexEntry: ; 0x1d12c0
+	db "HANDSTAND@" ; species name
+	dw 407, 1060 ; height, weight
+
+	db   "After doing a"
+	next "handstand to"
+	next "throw off the"
+	page "opponent's timing,"
+	next "it presents its"
+	next "fancy kick moves.@"