chore: Add doc(hidden)

Author: ids1024

backend/src/board.rs

@@ -8,6 +8,7 @@ use std::{cell::Cell, collections::HashMap, rc::Rc};
 use crate::{BoardId, Daemon, DerefCell, Key, KeyMap, Layer, Layout};
 
 #[derive(Default)]
+#[doc(hidden)]
 pub struct BoardInner {
     daemon: DerefCell<Rc<dyn Daemon>>,
     board: DerefCell<BoardId>,

backend/src/lib.rs

@@ -25,6 +25,7 @@ pub use self::{
 use daemon::*;
 
 #[derive(Default)]
+#[doc(hidden)]
 pub struct BackendInner {
     daemon: DerefCell<Rc<dyn Daemon>>,
     boards: RefCell<HashMap<BoardId, Board>>,