Update README. Add Used technologies.

Author: valdeci-dev

README.md

@@ -4,9 +4,40 @@ This project contains some examples of how use TDD with Ruby on Rails.
 
 ### Used technologies
 
-The main technologies used in this project were:
+The main technologies and Rails gems used in this project are:
 
-* [Capybara](https://) - Capybara description.
-* [Rspec](https://) - Rspec description.
-* [Cucumber](https://) - Cucumber description.
+#### Development
+* [Rails 5](http://rubyonrails.org/) - a web-application framework that includes everything needed to create 
+database-backed web applications according to the Model-View-Controller (MVC) pattern.
+* [Devise](https://github.com/plataformatec/devise) - flexible authentication solution for Rails with Warden.   
+* [CarrierWave](https://github.com/carrierwaveuploader/carrierwave) - classier solution for file uploads for Rails,
+Sinatra and other Ruby web frameworks.
+* [The Twitter Ruby Gem](https://github.com/sferik/twitter) - a Ruby interface to the Twitter API.
+* [ActiveModelSerializers](https://github.com/rails-api/active_model_serializers) - ActiveModel::Serializer 
+implementation and Rails hooks.
 
+#### Testing
+* [Capybara](https://github.com/teamcapybara/capybara) - acceptance test framework for web applications.
+* [Rspec](https://github.com/rspec/rspec-rails) - testing framework for Rails 3.x, 4.x and 5.0.
+* [Cucumber](https://cucumber.io/) - software tool used by computer programmers for testing other software. It runs 
+automated acceptance tests written in a behavior-driven development (BDD) style 
+* [Minitest](https://github.com/seattlerb/minitest) - provides a complete suite of testing facilities supporting TDD, 
+BDD, mocking, and benchmarking.
+* [Database Cleaner](https://github.com/DatabaseCleaner/database_cleaner) - strategies for cleaning databases in Ruby.
+ Can be used to ensure a clean state for testing.
+* [Shoulda Matchers](https://github.com/thoughtbot/shoulda-matchers) - provides RSpec- and Minitest-compatible 
+one-liners that test common Rails functionality. These tests would otherwise be much longer, more complex
+and error-prone.
+* [vcr](https://github.com/vcr/vcr) - use to record the test suite's HTTP interactions and replay them during future
+test runs for fast, deterministic and accurate tests.
+* [WebMock](https://github.com/bblimke/webmock) - library for stubbing and setting expectations on HTTP requests in Ruby.
+* [Selenium](https://github.com/SeleniumHQ/selenium) -  tool for writing automated tests of websites. It aims to mimic 
+the behaviour of a real user, and as such interacts with the HTML of the application.
+* [Factory Girl](https://github.com/thoughtbot/factory_girl_rails) - a library for setting up Ruby objects as test data. 
+* [Rails Controller Testing](https://github.com/rails/rails-controller-testing) - brings back `assigns` and `assert_template` 
+to the Rails tests.  
+
+#### Database      
+
+As this is a simple application that don't need great data persistence the default database used when a new Ruby on Rails
+application is created has been used: [SQlite3](https://www.sqlite.org/)