Removed wrong reference to cookbook

The /cookbook/request/mime_type article does not contain an example to
register a kernel listener since 2.5
Update index.rst

Correction d'une erreur sémantique
Update introduction.rst

fix spelling
Update doctrine.rst

Dans la section "Requêter des objets avec DQL"
Deprecated: getEntityManager is deprecated since Symfony 2.1. Use getManager instead
fix typo s/Cela ajouter/Cela ajoute
Merge pull request #558 from grifx/patch-1

fix typo s/Cela ajouter/Cela ajoute
Merge pull request #556 from anaphel/patch-1

Update doctrine.rst
Merge pull request #554 from astucieuxzephyr/patch-2

Update index.rst
Merge pull request #559 from symfony-fr/2.5

Merging 2.5 to master
Merge pull request #555 from CoreFloDev/patch-1

Update introduction.rst
Merge pull request #548 from gquemener/remove_incorrect_reference

Removed wrong reference to cookbook
Merge branch '2.5' into 2.4
Merging #552