Docs: Demonstrate how to load custom reporter from local script

It is not currently valid to pass `./foo.js` to `--reporter` because
cli/run.js and cli/find-reporter.js would be running require() relative
to where the qunit package is installed instead of the project directory.

We could make this work in the future, but this is how it works today.

docs/cli.md

@@ -133,7 +133,16 @@ By default, the TAP reporter is used. This allows you to pair QUnit with any [TA
 qunit test/ | tap-min
 ```
 
-To change the reporting from QUnit itself, use `qunit --reporter <name>` to set a different reporter, where `<name>` can be the name of a built-in reporter, or an Node module that implements the [QUnit Reporter API](./api/callbacks/QUnit.on.md#reporter-api). The reporter will be loaded and initialised automatically.
+To change the reporting from QUnit itself, use `qunit --reporter <name>` to set a different reporter, where `<name>` can be the name of a built-in reporter, or a Node module (e.g. npm package) that implements the [QUnit Reporter API](./api/callbacks/QUnit.on.md#reporter-api). The reporter will be loaded and initialised automatically.
+
+To load a reporter from a local Node.js script, use `--require` instead.
+
+Example:
+
+```sh
+qunit --reporter tap
+qunit --reporter qunit-reporter-example
+```
 
 Built-in reporters:
 
@@ -157,6 +166,8 @@ qunit --require ./test/setup.js
 QUnit.config.noglobals = true;
 QUnit.config.notrycatch = true;
 
+require('../build/my-custom-reporter.js').init(QUnit);
+
 global.MyApp = require('./index');
 ```
 

test/cli/fixtures/npm-reporter/package.json

@@ -1,7 +1,9 @@
 {
   "version": "1.0.0",
   "name": "npm-reporter",
+  "private": true,
   "keywords": [
+    "qunit-plugin",
     "js-reporter"
   ]
 }