WTO: Store DB.nomics JSON files for monthly_xm_manuf_price_e.xls

Child of #2 (closed)

Dataset: Monthly changes in export and import price of manufactured goods

• As a search engine indexer,
• I want to find category.json, dataset.json, series.json and observations.tsv files corresponding to the XLS file monthly_xm_manuf_price_e.xls of the "monthly" category,
• In order to index them.

Acceptance criteria

• Each dataset MUST be in the "monthly" category.
• "..." cells MUST be declared in "unknown_values" property of series.json

Resources

• WTO fetcher description