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/marowak.asm

@@ -0,0 +1,10 @@
+; MarowakPokedexEntry: ; 0x1b90d2
+	db "BONEKEEPER@" ; species name
+	dw 303, 990 ; height, weight
+
+	db   "Somewhere in the"
+	next "world is a ceme-"
+	next "tery just for"
+	page "MAROWAK. It gets"
+	next "its bones from"
+	next "those graves.@"