Add EXAMPLES table to help output

[johndugan]

When executing myapp --help, a nice table is presented with the information provided in cli.js.

I believe the meow API allows for an examples object to be defined. It would be great to have this added to the help text tables.

// cli.js

//...code

const examples = {
    'Greet by first name': 'myapp greet --first-name Bob'
};

const helpText = meowHelp({
    name: 'content',
    flags: flags,
    commands: commands,
    examples: examples
});

// ...rest of code