fix typo in comment, fixes preboot#75

Author: phra

webpack.config.js

@@ -130,7 +130,7 @@ module.exports = function makeWebpackConfig() {
   // ISTANBUL LOADER
   // https://github.com/deepsweet/istanbul-instrumenter-loader
   // Instrument JS files with istanbul-lib-instrument for subsequent code coverage reporting
-  // Skips node_modules and files that end with .test
+  // Skips node_modules and files that end with .spec.js
   if (isTest) {
     config.module.rules.push({
       enforce: 'pre',