[docs] Describe passing the reporter object through the API (DevExpress#4757)

Author: VasilyStrelyaev

Diff for: .gitignore

@@ -12,3 +12,4 @@ yarn.lock
 package-lock.json
 Gemfile.lock
 .npmrc
+.DS_Store

Diff for: docs/articles/documentation/extending-testcafe/reporter-plugin/README.md

@@ -21,6 +21,8 @@ To create a reporter plugin, go through the following steps.
 * [Using the Reporter Development Version](#using-the-reporter-development-version)
 * [Publishing the Reporter to npm](#publishing-the-reporter-to-npm)
 
+> You can also specify a reporter object in the [TestCafe programming interface](../../using-testcafe/programming-interface/runner.md#specifying-a-custom-reporter). However, a reporter plugin is easier to reuse and maintain.
+
 ## Generating a Reporter Project
 
 First, install [Yeoman](http://yeoman.io) and `generator-testcafe-reporter` using [npm](https://www.npmjs.com/).

Diff for: docs/articles/documentation/using-testcafe/programming-interface/runner.md

@@ -314,13 +314,15 @@ Configures TestCafe's reporting feature.
 
 ```text
 reporter(name, output) → this
-reporter([ name | { name, output }]) → this
+reporter(fn) → this
+reporter([ name | { name, output } | fn ]) → this
 ```
 
 Parameter                | Type                        | Description                                     | Default
 ------------------------ | --------------------------- | ----------------------------------------------- | --------
-`name`                   | String              | The name of the [reporter](../common-concepts/reporters.md) to use.
+`name`                   | String      | The name of the [reporter](../common-concepts/reporters.md).
 `output` *(optional)* | String | Writable Stream implementer | The file path where the report is written or the output stream. | `stdout`
+`fn` | A function that [returns a custom reporter object](#specifying-a-custom-reporter).
 
 To use a single reporter, specify a reporter name and, optionally, an output target as the second parameter.
 
@@ -351,6 +353,30 @@ runner.reporter(['spec', {
 }]);
 ```
 
+#### Specifying a Custom Reporter
+
+You can implement a [custom reporter](../../extending-testcafe/reporter-plugin/README.md) in the code that launches tests. This approach allows you to implement your reporter faster if you need it for a single project or do not want to publish a reporter plugin.
+
+Pass a *function* that returns the custom reporter object to the `runner.reporter` method.
+
+```js
+import { createTestCafe } from 'testcafe';
+
+const customReporter = () => {
+    return {
+        async reportTaskStart (startTime, userAgents, testCount) { /* ... */ },
+        async reportFixtureStart (name, path, meta) { /* ... */ },
+        async reportTestDone (name, testRunInfo, meta) { /* ... */ },
+        async reportTaskDone (endTime, passed, warnings, result) { /* ... */ }
+    };
+};
+
+const testcafe = await createTestCafe(/* [...] */);
+const runner   = testcafe.createRunner();
+
+await runner.reporter(customReporter);
+```
+
 #### Implementing a Custom Stream
 
 ```js