/// Specifies the primary text direction for the `name`, `short_name`, and
/// `description` members.
///
/// ## Example
/// ```rust
/// # extern crate webmanifest;
/// # extern crate failure;
/// # use webmanifest::{Manifest, Direction};
/// # fn main() -> Result<(), failure::Error> {
/// let name = "My Cool Application";
/// let lang = "en-US";
/// let manifest = Manifest::builder(name)
/// .direction(Direction::Ltr)
/// .build()?;
/// # Ok(())}
/// ```