Add locale to preview path

[tiacop]

If the datoCMS project is multilang add the locale to the preview path

[wbobeirne]

I assume you intend to publish your own fork of this plugin? I can't accept this PR as submitted, as it changes a lot of underlying things (module name, author etc.)

Appreciate the example code of pulling the locale from a field though, I may use this to rework the plugin as outlined here: #2 (comment) and include locale as one of the fields.

[tiacop]

Thanks for your answer and it's OK! I thought, having so many preview plugins is confusing, but in the end I forked yours and i'm working on a "multilang & field addon" ... https://github.com/tiacop/datocms-plugin-nextjs-preview. So the preview link can no longer be overlooked :)

[wbobeirne]

Sounds good, feel free to keep riffing on that one!