clarify comment

crates/eframe/src/web/text_agent.rs

@@ -99,12 +99,14 @@ impl TextAgent {
         ime: Option<egui::output::IMEOutput>,
         canvas: &web_sys::HtmlCanvasElement,
     ) -> Result<(), JsValue> {
-        // don't move the text agent on mobile
+        // Mobile keyboards don't follow the text input it's writing to,
+        // instead typically being fixed in place on the bottom of the screen,
+        // so don't bother moving the text agent on mobile.
         if is_mobile() {
             return Ok(());
         }
 
-        // don't move the text agent unless the position actually changed:
+        // Don't move the text agent unless the position actually changed:
         if self.prev_ime_output.get() == ime {
             return Ok(());
         }