/**
 * @class Ext.exporter.file.ooxml.Relationships
 * @extend Ext.exporter.file.ooxml.Xml
 * @private
 */
 
/**
 * @method addRelationship
 * Convenience method to add relationships.
 * @param {Object/Array} config
 * @return {Ext.exporter.file.ooxml.Relationship/Ext.exporter.file.ooxml.Relationship[]}
 */