docs(array filter): add example using array filters

test/functional/operation_array_update_example_test.js

@@ -0,0 +1,40 @@
+'use strict';
+const setupDatabase = require('./shared').setupDatabase;
+const expect = require('chai').expect;
+
+describe('Array Filter Update Example', function() {
+  before(function() {
+    return setupDatabase(this.configuration);
+  });
+
+  it('supports using array filters when updating one', {
+    metadata: {
+      requires: {
+        mongodb: '>=3.6.x',
+        topology: ['single']
+      }
+    },
+
+    test: function(done) {
+      const configuration = this.configuration;
+      const client = configuration.newClient(configuration.writeConcernMax(), { poolSize: 1 });
+      client.connect(function(err, client) {
+        const db = client.db(configuration.db);
+        const collection = db.collection('arrayFilterUpdateExample');
+
+        // 3. Exploiting the power of arrays
+        collection.updateOne(
+          { _id: 1 },
+          { $set: { 'a.$[i].b': 2 } },
+          { arrayFilters: [{ 'i.b': 0 }] },
+          function updated(err, result) {
+            expect(err).to.equal(null);
+            expect(result).to.exist;
+            client.close();
+            done();
+          }
+        );
+      });
+    }
+  });
+});