feat: Add support for `Errorf`

[wafuwafu13]

I want to add support for Errorf.

Before

func exampleFunc() error {
    ex, err := foo()
    red := color.New(color.FgRed)
    if err != nil {
        return fmt.Errorf(red.Sprintf("this is error: %s", err))
    }
...
}

After

func exampleFunc() error {
    ex, err := foo()
    red := color.New(color.FgRed)
    if err != nil {
        return red.Errorf("this is error: %s", err)
    }
...
}

[fatih]

Hi @wafuwafu13 Thanks for your contribution.

Errors are not meant to be colorized. They are values, and adding a color means you're creating a new error from scratch.