Change 'To run' to 'To use' in all README.md files

As in:

    sgit -e 's/# To run/# To use/g' '*README.md'

This makes consistent the message for how to use the program. 'How to
use' was chosen because one can run a program just by doing './foo' but
that doesn't imply that's how to use it but the purpose of the section
is how to use it.

2013/birken/README.md

@@ -11,7 +11,7 @@ Michael Birken\
 make alt
 ```
 
-## To run:
+## To use:
 
 To see why we recommend the alternate version instead of the original version,
 see the [original code](#original-code) section.