Add some doc comments around the video struct

agb/src/display/video.rs

@@ -4,6 +4,10 @@ use super::{
     tiled::{Tiled0, VRamManager},
 };
 
+/// The video struct controls access to the video hardware.
+/// It ensures that only one video mode is active at a time.
+///
+/// Most games will use tiled modes, as bitmap modes are too slow to run at the full 60 FPS.
 #[non_exhaustive]
 pub struct Video {}
 
@@ -18,6 +22,7 @@ impl Video {
         unsafe { Bitmap4::new() }
     }
 
+    /// Tiled 0 mode provides 4 regular, tiled backgrounds
     pub fn tiled0(&mut self) -> (Tiled0, VRamManager) {
         (unsafe { Tiled0::new() }, VRamManager::new())
     }