test: added a test comment

Added comments to the tests to better describe what the test is doing.

PR-URL: https://github.com/nodejs/node/pull/16003
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/sequential/test-debugger-debug-brk.js

@@ -1,8 +1,12 @@
 'use strict';
 const common = require('../common');
 common.skipIfInspectorDisabled();
-const fixtures = require('../common/fixtures');
+
+// This test ensures that the debug-brk flag will spin up a new process and
+// wait, rather than exit.
+
 const assert = require('assert');
+const fixtures = require('../common/fixtures');
 const spawn = require('child_process').spawn;
 
 // file name here doesn't actually matter since