/// Converts the first character of the input string to uppercase and the remaining characters to lowercase.
///
/// # Arguments
///
/// * `s` - The input string to be capitalized.
///
/// # Returns
///
/// Returns a new string with the first character capitalized and the remaining characters in lowercase.
///
/// # Example
///
/// ```rust
/// use lorust::capitalize;
///
/// let capitalized = capitalize("FRED".to_string());
/// assert_eq!(capitalized, "Fred");
/// ```