Update docs

doc/changelog.asciidoc

@@ -64,6 +64,9 @@ Added
   settings might stop working. As a (currently undocumented) escape hatch, this
   version adds a `QUTE_DARKMODE_VARIANT=qt_515_2` environment variable which can
   be set to get the correct behavior in (transitive) situations like this.
+- New `--desktop-file-name` commandline argument, which can be used to customize
+  the desktop filename passed to Qt (which is used to set the `app_id` on
+  Wayland).
 - New userscripts:
   - `kodi` to play videos in Kodi
   - `qr` to generate a QR code of the current URL

doc/qutebrowser.1.asciidoc

@@ -62,6 +62,9 @@ show it.
 *--backend* '{webkit,webengine}'::
     Which backend to use.
 
+*--desktop-file-name* 'DESKTOP_FILE_NAME'::
+    Set the base name of the desktop entry for this application. Used to set the app_id under Wayland. See https://doc.qt.io/qt-5/qguiapplication.html#desktopFileName-prop
+
 === debug arguments
 *-l* '{critical,error,warning,info,debug,vdebug}', *--loglevel* '{critical,error,warning,info,debug,vdebug}'::
     Override the configured console loglevel