fix(package): require Node 6+

gr2m · gr2m · commit f1c0e2f5c94e · 2019-04-29T08:52:47.000-07:00
/cc @hongarc
diff --git a/package.json b/package.json
@@ -50,7 +50,7 @@
     "textlint-rule-rousseau": "^1.4.5"
   },
   "engines": {
-    "node": ">=4"
+    "node": ">=6"
   },
   "files": [
     "bin",
