docs: mention launch.json (#404)

## PR Checklist

- [x] Addresses an existing open issue: fixes #000
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/template-typescript-node-package/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/template-typescript-node-package/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Mentions the current test file launch script.

Author: JoshuaKGoldberg

.github/DEVELOPMENT.md

@@ -61,3 +61,8 @@ pnpm run test --coverage
 
 Note that [console-fail-test](https://github.com/JoshuaKGoldberg/console-fail-test) is enabled for all test runs.
 Calls to `console.log`, `console.warn`, and other console methods will cause a test to fail.
+
+### Debugging Tests
+
+This repository includes a [VS Code launch configuration](https://code.visualstudio.com/docs/editor/debugging) for debugging unit tests.
+To launch it, open a test file, then run _Debug Current Test File_ from the VS Code Debug panel (or press F5).