fix: clearer jsdoc for behavior of headless when devtools is true (#7748)

The existing comment suggests that only the default changes–however, even if you set `devtools: false` and `headless: true`, Puppeteer will still open with headful.

src/node/LaunchOptions.ts

@@ -36,7 +36,7 @@ export interface BrowserLaunchArgumentOptions {
   userDataDir?: string;
   /**
    * Whether to auto-open a DevTools panel for each tab. If this is set to
-   * `true`, then `headless` will be set to `false` automatically.
+   * `true`, then `headless` will be forced to `false`.
    * @defaultValue `false`
    */
   devtools?: boolean;