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

tools/sym_comments.py

@@ -2,7 +2,7 @@
 # -*- coding: utf-8 -*-
 
 """
-Usage: ./sym_comments.py file.asm [pokecrystal.sym] > file_commented.asm
+Usage: python3 sym_comments.py file.asm [pokecrystal.sym] > file_commented.asm
 
 Comments each label in file.asm with its bank:address from the sym file.
 """

tools/toc.py

@@ -3,6 +3,7 @@
 
 """
 Usage: python3 toc.py [-n] files.md...
+
 Replace a "## TOC" heading in a Markdown file with a table of contents,
 generated from the other headings in the file. Supports multiple files.
 Headings must start with "##" signs to be detected.