message: Fix docs for `aws_smithy_types::Number` converters
  Current docs:
  I learnt this trick from
diff: @@ -89,8 +89,10 @@ pub enum Number {
  }
  macro_rules! to_num_fn {
  - ($name:ident, $typ:ident) => {
  - /// Converts to a `$typ`. This conversion may be lossy.
  + ($name:ident, $typ:ident, $styp:expr) => {
  + #[doc = "Converts to a `"]
  + #[doc = $styp]
  + #[doc = "`. This conversion may be lossy."]
  pub fn $name(self) -> $typ {
  match self {
  Number::PosInt(val) => val as $typ,
  @@ -99,6 +101,10 @@ macro_rules! to_num_fn {
  }
  }
  };
  +
  + ($name:ident, $typ:ident) => {
  + to_num_fn!($name, $typ, stringify!($typ));
  + };
  }
  impl Number {
  