gitignore: comment the items

So people do not remove it because that don't see why.

grunt-init-project/root/gitignore-file

@@ -1,7 +1,10 @@
+#Dependencies defined in `package.json` got via `npm install`
 /node_modules/
 
+#Generated when running tests from cli via `npm test` / `grunt test`
 /test_runner.js
 
+#Generated when `grunt devel`, `grunt deploy` or `grunt deploy:lambda`
 /config.js
 /the.js
 /lambda/the.js