README.md in bright_serializer-0.2.5 vs README.md in bright_serializer-0.3.0

@@ -1,7 +1,8 @@
 [![Actions Status](https://github.com/petalmd/bright_serializer/workflows/Build/badge.svg)](https://github.com/petalmd/bright_serializer/actions?query=workflow%3ABuild)
 [![Gem Version](https://badge.fury.io/rb/bright_serializer.svg)](https://badge.fury.io/rb/bright_serializer)
+[![Coverage Status](https://coveralls.io/repos/github/petalmd/bright_serializer/badge.svg?branch=master)](https://coveralls.io/github/petalmd/bright_serializer?branch=master)
 
 # BrightSerializer
 
 This is a very light and fast gem to serialize object in a Ruby project.
 
@@ -29,16 +30,16 @@
 
 ```ruby
 class AccountSerializer
   include BrightSerializer::Serializer
   attributes :id, :first_name, :last_name
-  
+
   # With a block
   attribute :name do |object|
     "#{object.first_name} #{object.last_name}"
   end
-  
+
   # With a block shorter
   attribute :created_at, &:to_s
 end
 
 AccountSerializer.new(Account.first).to_h
@@ -51,11 +52,11 @@
 
 ```ruby
 class AccountSerializer
   include BrightSerializer::Serializer
   attributes :id, :first_name, :last_name
-  
+
   attribute :friend do |object, params|
     object.is_friend_with? params[:current_user]
   end
 end
 
@@ -63,18 +64,18 @@
 AccountSerializer.new(Account.first, params: { current_user: current_user }).to_json
 ```
 
 ### Conditional Attributes
 
-Attribute can be remove from serialization by passing a `proc` to the option `if`. If the proc return `true` the attibute 
- will be serialize. `object` and `params` or accessible. 
+Attribute can be remove from serialization by passing a `proc` to the option `if`. If the proc return `true` the attibute
+ will be serialize. `object` and `params` or accessible.
 
 ```ruby
 class AccountSerializer
   include BrightSerializer::Serializer
   attributes :id, :first_name, :last_name
-  
+
   attribute :email, if: -> { |object, params| params[:current_user].is_admin? }
 end
 ```
 
 ### Transform keys
@@ -116,33 +117,58 @@
 end
 
 class AccountSerializer
   include BrightSerializer::Serializer
   attributes :id, :first_name, :last_name
-  
+
   attribute :friends do |object|
     FriendSerializer.new(object.friends)
   end
 end
 ```
 
 ### Entity
 
 You can define the entity of your serializer to generate documentation with the option `entity`.
-The feature was build to work with [grape-swagger](https://github.com/ruby-grape/grape-swagger). 
+The feature was build to work with [grape-swagger](https://github.com/ruby-grape/grape-swagger).
 For more information about defining a model entity see the [Swagger documentation](https://swagger.io/specification/v2/?sbsearch=array%20response#schema-object).
 
 ```ruby
 class AccountSerializer
   include BrightSerializer::Serializer
   attribute :id, entity: { type: :string, description: 'The id of the account' }
   attribute :name
 
   attribute :friends,
-    entity: { 
+    entity: {
       type: :array, items: { ref: 'FriendSerializer' }, description: 'The list the account friends.'
      } do |object|
     FriendSerializer.new(object.friends)
+  end
+end
+
+```
+Callable values are supported.
+
+```ruby
+{ entity: { type: :string, enum: -> { SomeModel::ENUMVALUES } } }
+```
+
+### Instance
+
+If you have defined instance methods inside your serializer you can access them inside block attribute.
+
+```ruby
+class AccountSerializer
+  include BrightSerializer::Serializer
+  attributes :id, :name
+
+  attribute :print do |object|
+    print_account(object)
+  end
+
+  def print_account(object)
+    "Account: #{object.name}"
   end
 end
 ```
 
 ## Development