Merge branch '2.8' into 3.4

* 2.8:
  correct a typo in a namespace loading
  Fixed the link to Functional Tests
  Update templating.rst
  Update doctrine.rst

Author: javiereguiluz

bundles/extension.rst

@@ -35,8 +35,8 @@ but usually you would simply extend the
     // src/Acme/HelloBundle/DependencyInjection/AcmeHelloExtension.php
     namespace Acme\HelloBundle\DependencyInjection;
 
-    use Symfony\Component\HttpKernel\DependencyInjection\Extension;
     use Symfony\Component\DependencyInjection\ContainerBuilder;
+    use Symfony\Component\DependencyInjection\Extension\Extension;
 
     class AcmeHelloExtension extends Extension
     {

doctrine.rst

@@ -201,10 +201,11 @@ can automatically generate an empty ``test_project`` database for you:
 
     .. caution::
 
-        MySQL sets a `limit of 767 bytes for the index key prefix`_. When using
-        ``utf8mb4``, string columns with 255 character length surpass that limit.
-        This means that any column of type ``string`` and ``unique=true`` must
-        set its maximum ``length`` to ``190``. Otherwise, you'll see this error:
+        There is a `limit of 767 bytes for the index key prefix`_ when using
+        InnoDB tables in MySQL 5.6 and earlier versions. String columns with 255
+        character length and ``utf8mb4`` encoding surpass that limit. This means
+        that any column of type ``string`` and ``unique=true`` must set its
+        maximum ``length`` to ``190``. Otherwise, you'll see this error:
         *"[PDOException] SQLSTATE[42000]: Syntax error or access violation:
         1071 Specified key was too long; max key length is 767 bytes"*.
 

templating.rst

@@ -407,9 +407,8 @@ ease the work of the template designer. In PHP, the templating system provides
 an extensible *helper* system that provides useful features in a template
 context.
 
-You've already seen a few built-in Twig tags (``{% block %}`` & ``{% extends %}``)
-as well as an example of a PHP helper (``$view['slots']``). Here you will learn a
-few more.
+You've already seen a few built-in Twig tags like ``{% block %}`` and
+``{% extends %}``. Here you will learn a few more.
 
 .. index::
    single: Templating; Including other templates

testing.rst

@@ -47,7 +47,7 @@ Unit Tests
 
 A unit test is a test against a single PHP class, also called a *unit*. If you
 want to test the overall behavior of your application, see the section about
-`Functional Tests`_.
+:ref:`Functional Tests <functional-tests>`.
 
 Writing Symfony unit tests is no different from writing standard PHPUnit
 unit tests. Suppose, for example, that you have an *incredibly* simple class