Update usage doc comments for some tools/*.py scripts

tools/palfix.py

@@ -1,6 +1,14 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+"""
+Usage: python palfix.py image.png
+
+Fix the palette format of the input image. Colored images (Pokémon or trainer
+sprites) will become indexed, with a palette sorted {white, light color, dark
+color, black}. Grayscale images will become two-bit grayscale.
+"""
+
 from __future__ import print_function
 
 import sys