Write docs for shipping label printing

[bstocks]

depends on #260

[luiginica]

Hi,
I manage 3 marketplace stores - Amazon, Opencart and woocommerce - and for labels I'm using https://shiprobot.com/ to generate UPS and CanadaPost (contract and mastercard account types) labels. They also have an options to generate labels from a csv.
From my point of view a first step in having the shipping label feature will be to have an option to export orders to a .csv file.

Regards,
Luigi

[aaronjudd]

Looks like an API integration into shiprobot would be very simple to do. I don't think you'd need to export to CSV first. However, you can use the mongo shell to export CSV as well as json.
for example you could do:
mongoexport --csv --db meteor --collection orders