Add support for "direction" property on <TextLoop> element

[leggetter]

Allow up or down scrolling to be set via a direction property supporting value up or down.

Added the following example:

const DirectionExample: React.FunctionComponent = (): JSX.Element => (
    <Section>
        <Title>Default</Title>
        <Example>
            <TextLoop direction="down">
                <span>Trade faster</span>
                <span>Increase sales</span>
                <span>Stock winners</span>
            </TextLoop>{" "}
            and{" "}
            <TextLoop direction="up">
                <span>be awesome</span>
                <span>win big</span>
                <span>live the dream</span>
            </TextLoop>
        </Example>
    </Section>
);

Based off of an original update by @ jaredsilver.