Simplify destructuring this array

Library/Homebrew/cmd/doctor.rb

@@ -625,11 +625,8 @@ def check_for_config_scripts
 
     EOS
 
-    config_scripts.each do |pair|
+    config_scripts.each do |dir, files|
-      dn = pair[0]
+      files.each { |fn| s << "    #{dir}/#{fn}\n" }
-      pair[1].each do |fn|
-        s << "    #{dn}/#{fn}\n"
-      end
     end
     s
   end