Add a language switching widget to the user guide page layout

[emlys]

It would be nice to be able to switch languages on any page of the user guide. Something like a translation icon in the top corner, which opens a dropdown menu of languages, which redirect to the appropriate page. This would be nice, but not necessary for the initial translation effort - we'll link to the user guide in each language from the downloads page.

[dcdenu4]

We talked about this briefly in a huddle and still think it would be nice to do. It might be possible through Templates, Emily and James had an inkling of a possible future implementation pathway.