Add vscode debug example (#6)

Author: Changqing-JING

docs/launch.example.json

@@ -0,0 +1,19 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "type": "node",
+      "request": "launch",
+      "name": "Launch Program",
+      "skipFiles": ["<node_internals>/**"],
+      "program": "${workspaceFolder}/node_modules/mocha/bin/_mocha",
+      "args": [
+        "--timeout",
+        "10000",
+        "--colors",
+        "${workspaceFolder}/dist/tests/**/*.js"
+      ],
+      "outFiles": ["${workspaceFolder}/dist/**/*.js"]
+    }
+  ]
+}