message: Fix renderable_cursor method documentation
  This method no longer returns an `Option` since
diff: @@ -108,8 +108,6 @@ impl<'a> RenderableContent<'a> {
  }
  /// Assemble the information required to render the terminal cursor.
  - ///
  - /// This will return `None` when there is no cursor visible.
  fn renderable_cursor(&mut self, cell: &RenderableCell) -> RenderableCursor {
  // Cursor colors.
  let color = if self.terminal_content.mode.contains(TermMode::VI) {
  