Update Korean Translation, fix some typo.

* 'master' of github.com:rwldrn/idiomatic.js:
  Update Korean Translation
  Fix typo
  update translation 4.2
  update korean translation 3.B, fix misstake (writing 3.B.2.3 twice)
  translate 2.B.1.3
  translate 2.E
  update contributors list
  add Preface
  Fix indent again
  fix indent issue
  hand merge from english doc
  fix indexing error

* 'master' of https://github.com/rubystream/idiomatic.js:
  second iteration
  first iteration
  introduce the serbian translation

…ithub](https://github.com/rubystream)

Fixed broken link to Idan's old github username.

Fix error in sintax pt-BR

Updating Serbian translations

fix some typos and add some "better french" (I hope so) translations

The word "serem" in portuguese is incorrect as it is explained [here](http://jovempan.uol.com.br/noticias/comportamento-educacao/concordancia-verbal-ser-ou-serem.html).

Greek translation

The therm "coercion" does not exist in French. While the equivalent could be "coercition", the word "conversion" is the most commonly used.

* Update code quality tools list

* Remove a broken link

Adding Jest among the testing frameworks.