feat: add list of recipirnts to campaign

lib/campaign.model.js

@@ -109,6 +109,21 @@ const CampaignSchema = new Schema({
    */
   sender: Contact,
 
+  /**
+   * @name to
+   * @description receiver(s) of the campaign message i.e e-mail receiver, 
+   * sms receiver etc.
+   *
+   * Used for campaign with receiver(s) less than 100. For larger receiver list 
+   * use criteria and supply `fetchContacts` to postman.
+   * 
+   * @type {Contact[]}
+   * @since 0.1.0
+   * @version 1.0.0
+   * @instance
+   */
+  to: [Contact],
+
   /**
    * @name subject
    * @description subject of the campaign i.e email title etc

test/unit/campaign.schema.spec.js

@@ -49,6 +49,13 @@ describe('Campaign Schema', () => {
     expect(sender.instance).to.be.equal('Embedded');
   });
 
+  it('should have to field', () => {
+    const to = Campaign.path('to');
+
+    expect(to).to.exist;
+    expect(to.instance).to.be.equal('Array');
+  });
+
   it('should have subject field', () => {
     const subject = Campaign.path('subject');