Add ng words for post/update

app/models/admin/ng_word.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class Admin::NgWord
+  class << self
+    def reject?(text)
+      ng_words.any? { |word| text.include?(word) }
+    end
+
+    private
+
+    def ng_words
+      Setting.ng_words
+    end
+  end
+end