[cosmetic] Booby trap in the first code example

[kfsone]

Right near the top of the readme, you demonstrated:

    program.add_argument("-v", "--verbose"); // parameter packing

which leads the user straight into their first collision:

Optional arguments:
-h --help       shows help message and exits
-v --version    prints version information and exits
-v --verbose   ...

It would be helpful if the "-v" on "--version" was optional.