update rails_best_practices/always_add_db_index description

Author: flyerhzm

lib/rails_best_practices/always_add_db_index.rb

@@ -2,6 +2,9 @@
 
 Synvert::Rewriter.new 'rails_best_practices', 'always_add_db_index' do
   description <<~EOS
+    Review db/schema.rb file to make sure every reference key has a database index.
+
+    See the best practice details here https://rails-bestpractices.com/posts/2010/07/24/always-add-db-index/
   EOS
 
   call_helper 'rails/parse'

spec/rails_best_practices/always_add_db_index_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-RSpec.describe 'Rails always add db index' do
+RSpec.describe 'Rails Best Practices always add db index' do
   before { load_helpers(%w[helpers/parse_rails]) }
 
   context 'index exists' do
@@ -100,9 +100,7 @@ class Picture < ApplicationRecord
         belongs_to :imageable, polymorphic: true
       end
     EOF
-    let(:warnings) { [
-      '/db/schema.rb#6: always add db index pictures => ["imageable_type", "imageable_id"]',
-    ] }
+    let(:warnings) { ['/db/schema.rb#6: always add db index pictures => ["imageable_type", "imageable_id"]'] }
 
     include_examples 'warnable'
   end
@@ -124,9 +122,7 @@ class Comment < ApplicationRecord
         belongs_to :commentor, foreign_key: :user_id
       end
     EOF
-    let(:warnings) { [
-      '/db/schema.rb#6: always add db index comments => ["user_id"]'
-    ] }
+    let(:warnings) { ['/db/schema.rb#6: always add db index comments => ["user_id"]'] }
 
     include_examples 'warnable'
   end