Merge branch '2.8' into 3.4

* 2.8:
  Missing root node in yaml example
  Fix a typo in security/impersonating_user.rst

Author: javiereguiluz

components/config/definition.rst

@@ -18,20 +18,21 @@ be a boolean value"):
 
 .. code-block:: yaml
 
-    auto_connect: true
-    default_connection: mysql
-    connections:
-        mysql:
-            host:     localhost
-            driver:   mysql
-            username: user
-            password: pass
-        sqlite:
-            host:     localhost
-            driver:   sqlite
-            memory:   true
-            username: user
-            password: pass
+    database:
+        auto_connect: true
+        default_connection: mysql
+        connections:
+            mysql:
+                host:     localhost
+                driver:   mysql
+                username: user
+                password: pass
+            sqlite:
+                host:     localhost
+                driver:   sqlite
+                memory:   true
+                username: user
+                password: pass
 
 When loading multiple configuration files, it should be possible to merge
 and overwrite some values. Other values should not be merged and stay as

security/impersonating_user.rst

@@ -96,7 +96,7 @@ to show a link to exit impersonation:
 
 In some cases you may need to get the object that represents the impersonator
 user rather than the impersonated user. Use the following snippet to iterate
-over the user's roles until you find one that a ``SwitchUserRole`` object::
+over the user's roles until you find one that is a ``SwitchUserRole`` object::
 
     use Symfony\Component\Security\Core\Role\SwitchUserRole;
     use Symfony\Component\Security\Core\Security;