refactor: replace var with const in example

[KARLE-ATHARVA]

This PR improves JavaScript best practices by replacing var with const.

[simon04]

There's a huge list of additional var occurrences in the code. Do you want to work on all?

> git grep --word-regexp var assets/javascripts/
assets/javascripts/app/app.js:    for (var doc of this.DOCS) {
assets/javascripts/app/app.js:    for (var type of doc.types.all()) {
assets/javascripts/app/app.js:    for (var slug of this.settings.getDocs()) {
assets/javascripts/app/app.js:        var doc;
assets/javascripts/app/app.js:      for (var key in features) {
assets/javascripts/app/app.js:        var value = features[key];
assets/javascripts/app/db.js:    for (var doc of app.docs.all()) {
assets/javascripts/app/db.js:    for (var name of objectStoreNames) {
assets/javascripts/app/db.js:      for (var path in data) {
assets/javascripts/app/db.js:        var content = data[path];
assets/javascripts/app/db.js:      var result = {};
assets/javascripts/app/db.js:    for (var doc of docs) {
assets/javascripts/app/db.js:        for (var key in this.cachedDocs) {
assets/javascripts/app/db.js:          var value = this.cachedDocs[key];
assets/javascripts/app/db.js:      for (var doc of docs) {
assets/javascripts/app/router.js:    for (var [path, method] of this.constructor.routes) {
assets/javascripts/app/searcher.js:      var objects = this.scoreMap[j];
assets/javascripts/app/searcher.js:      var char = chars[i];
assets/javascripts/app/settings.js:    for (var key of Settings.INTERNAL_KEYS) {
assets/javascripts/app/settings.js:    for (var layout of app.Settings.LAYOUTS) {
assets/javascripts/application.js:var init = function () {
assets/javascripts/collections/collection.js:    for (var object of objects) {
assets/javascripts/collections/collection.js:      for (var obj of object) {
assets/javascripts/collections/collection.js:    for (var model of this.models) {
assets/javascripts/collections/collection.js:    for (var model of this.models) {
assets/javascripts/collections/docs.js:    var next = () => {
assets/javascripts/collections/docs.js:    var fail = function (...args) {
assets/javascripts/collections/docs.js:    for (var doc of this.models) {
assets/javascripts/collections/docs.js:    var next = () => {
assets/javascripts/collections/docs.js:        for (var key in statuses) {
assets/javascripts/collections/docs.js:          var value = statuses[key];
assets/javascripts/collections/docs.js:        for (var slug in statuses) {
assets/javascripts/collections/docs.js:          var status = statuses[slug];
assets/javascripts/collections/docs.js:      for (var slug in statuses) {
assets/javascripts/collections/docs.js:        var status = statuses[slug];
assets/javascripts/collections/docs.js:        var doc = this.findBy("slug", slug);
assets/javascripts/collections/types.js:    for (var type of this.models) {
assets/javascripts/debug.js:  for (var key of Object.keys(view || {})) {
assets/javascripts/debug.js:    var value = view[key];
assets/javascripts/debug.js:        for (var k of Object.keys(value || {})) {
assets/javascripts/debug.js:          var v = value[k];
assets/javascripts/lib/ajax.js:    for (var key in ajax.defaults) {
assets/javascripts/lib/ajax.js:    for (var key in options.headers) {
assets/javascripts/lib/ajax.js:      var value = options.headers[key];
assets/javascripts/lib/cookies_store.js:      for (var cookie of document.cookie.split(/;\s?/)) {
assets/javascripts/lib/cookies_store.js:    for (var cookie of document.cookie.split(/;\s?/)) {
assets/javascripts/lib/events.js:      for (var name of event.split(" ")) {
assets/javascripts/lib/events.js:      for (var name of event.split(" ")) {
assets/javascripts/lib/events.js:      for (var name of event.split(" ")) {
assets/javascripts/lib/page.js:      var key = this.keys[i];
assets/javascripts/lib/page.js:      var value = iterable[i];
...