bin/build-metadata.js
function insertCountryAliases( data ) {
	Object.keys( aliases ).forEach( source => {
		data[ source ] = data[ aliases[ source ] ];
	} );
	return data;
}
function insertCountryAliases( data ) {
	Object.keys( aliases ).forEach( source => {
		data[ source ] = data[ aliases[ source ] ];
	} );
	return data;
}
Creates aliases. E.g. allows `uk` to be found by both `gb` and `uk`.
@param data