Fix localised content in pod.doc

[hellomichael]

Using !IfLocale within yaml doesn't get evaluated if used within pod.doc.

 {% set partial = pod.doc('/content/partials/footer.yaml').fields %}
 {{renderPartial.renderPartial(partial)}}

[jeremydw]

I think the issue here is we don't have any implicit localization available since pod.doc is just being called directly; the immediate fix is to pass in the current document's locale to the call to pod.doc:

 {% set partial = pod.doc('/content/partials/footer.yaml', doc.locale).fields %}
 {{renderPartial.renderPartial(partial)}}

We can leave this open in the meantime, to see if we can make calls to pod functions context-aware, or if we should close this out as working as intended or infeasible.

Note: Regardless, we should likely update the starter with this improvement.