Redirect to the English version if no localized help topic is available

1. Choose some localized (non-English) MuseScore interface and restart application to apply language change.
2. Invoke contextual help for some score element (for example, right-click on the score title).
3. On the opened web page, if there is no such handbook topic for the current language,
it will be reported that there is no available information.
4. But, if change in the browser address bar local language suffix (say, ru/) to en/, then a list of available English topic sections will appear.

It would be very handy to redirect to the English page version (with a list) in such cases automatically, or show a "hint" link to that page. Or, as a third alternative, insert the English content (link list) into the current localized page.