Fix error status of w3c-validation

Author: firefoxic

package.json

@@ -34,7 +34,7 @@
   "scripts": {
     "lint:spaces": "editorconfig-cli",
     "lint:styles": "stylelint \"source/styles/**/*.scss\"",
-    "lint:markup": "cd build && html-validator --quiet --continue",
+    "lint:markup": "cd build && html-validator --quiet",
     "lint:html": "linthtml build/**/*.html --config .linthtmlrc",
     "lint:bem": "gulp lintBem --silent",
     "lint:scripts": "eslint . --ignore-path .gitignore",