docs: say where quick compose opens its window in the pop-out notes

lib/popout/open.ts

@@ -1,6 +1,6 @@
 /**
- * Opens pop-out windows: one message, or a composer. Shared with the desktop
- * app's quick compose, which only has to call openComposerWindow.
+ * Opens pop-out windows: one message, or a composer. The desktop app's quick
+ * compose opens the same address from the shell.
  */
 
 import { appPath } from '@/lib/deep-links';

lib/popout/return-to-main.ts

@@ -16,7 +16,7 @@ const OPEN_WAIT_MS = RETURN_WAIT_MS - 2000;
 export type ReturnAnswer = 'shown' | 'busy';
 export type ReturnResult = ReturnAnswer | 'no-answer';
 
-/** From a pop-out: true once the composer is on screen in the main window. */
+/** From a pop-out: `shown` once the composer is on screen in the main window. */
 export function returnComposerToMain(payload: ComposePopoutPayload, accountId?: string | null, waitMs = RETURN_WAIT_MS): Promise<ReturnResult> {
   return new Promise((resolve) => {
     const returnId = newPopoutId();