update/doc comments + create assets collection

src/auth/authentication.js

@@ -3,6 +3,10 @@ const bcrypt = require('bcrypt');
 const joi = require("joi");
 const salt = 12;
 
+/**
+ * @param {MongoClient.collection} users db collection
+ * @returns {express.Router} authentication router
+ */
 module.exports = (users) => {
     const router = require("express").Router();