Improved explanation when creating a translation page

When editing a wiki page in-place you might have seen a "Translate" button if the edited page was missing a translation for the current locale. It wasn't obvious what this button does and the small notification message shown at the bottom of the page was hardly noticeable so we replaced it with a popover that is shown first when you enter edit mode and then whenever you hover the button. We also replaced the notification shown after clicking on the "Translate" button (to create the translation) with a popover on the page title input to invite you to translate the page title.