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/beedrill.asm

@@ -0,0 +1,10 @@
+; BeedrillPokedexEntry: ; 0x181c8a
+	db "POISON BEE@" ; species name
+	dw 303, 650 ; height, weight
+
+	db   "It uses sharp,"
+	next "poisonous stings"
+	next "to defeat prey,"
+	page "then takes the"
+	next "victim back to its"
+	next "nest for food.@"