fix doc

crates/bevy_dev_tools/src/fps_overlay.rs

@@ -15,9 +15,10 @@ use bevy_ui::node_bundles::TextBundle;
 /// A plugin that adds an FPS overlay to the Bevy application.
 /// Warning: This plugin will add [`FrameTimeDiagnosticsPlugin`] if it wasn't added before.
 ///
-/// Note: It is recommended to use native overlay of the rendering APi when possible. You can do
+/// Note: It is recommended to use native overlay of the rendering `API` when possible. You can do
 /// this by:
 /// - **Metal**: setting env variable `MTL_HUD_ENABLED=1`
+/// - **Vulkan** (specific to linux, requires Vulkan Mesa layers): `VK_INSTANCE_LAYERS='VK_LAYER_MESA_overlay'`
 pub struct FpsOverlayPlugin {
     /// Starting configuration of overlay, this can be later be changed through [`FpsOverlayConfig`] resource.
     pub config: FpsOverlayConfig,