README.md in pgtrigger-0.1.2 vs README.md in pgtrigger-0.1.3

@@ -13,11 +13,11 @@
 gem 'pgtrigger'
 ```
 
 And then execute:
 
-    $ bundle
+    $ bundle install
 
 Or install it yourself as:
 
     $ gem install pgtrigger
 
@@ -26,13 +26,15 @@
 Create a migration like this
 
 ```ruby
 class AddTriggerToSomeTable < ActiveRecord::Migration[5.1]
   def up
-    create_trigger(:table_name, :increase_order, before: [:insert]) do
+    create_trigger(:table_name, :increase_order, before: [:insert, :update], declare: {var_1: "text := 'test'", var_2: :integer}) do
         <<-TRIGGERSQL
-            NEW."order" = (
+            var_2 := -1
+
+            NEW."order" := (
               SELECT COALESCE(MAX("order"), 0) +1
               FROM table_name
             );
 
           RETURN NEW;
@@ -46,11 +48,12 @@
 end
 ```
 
 The create_trigger method, the first and second parameters are about table and name of trigger respectively.
 The third params can be hashes ```before:``` or ```after:```, passing string or array to indicate what event this trigger it will be executed.
+The param ```declare:``` is used to declare variables
 
-Yet is necessary to specify the down method, otherwise the trigger cannot be removed when execute migration rollback.
+**NOTE:** Yet is necessary to specify the down method, otherwise the trigger cannot be removed when execute migration rollback.
 
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.