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/hitmonchan.asm

@@ -0,0 +1,10 @@
+; HitmonchanPokedexEntry: ; 0x1b91a4
+	db "PUNCHING@" ; species name
+	dw 407, 1110 ; height, weight
+
+	db   "To increase the"
+	next "strength of all"
+	next "its punch moves,"
+	page "it spins its arms"
+	next "just before making"
+	next "contact.@"