minor #6982 [Ldap] Updated Ldap component documentation for 3.1 (csarrazi, javiereguiluz)

This PR was submitted for the 3.1 branch but it was merged into the 3.3 branch instead (closes #6982).

Discussion
----------

[Ldap] Updated Ldap component documentation for 3.1

| Q | A |
| --- | --- |
| Doc fix? | no |
| New docs? | yes |
| Applies to | 3.1, 3.2 |
| Fixed tickets | #5756 |

Unfortunately, I didn't have the time to update the docs since I have been pretty busy these last months, but like people say, better late than never!
The documentation has been updated for version 3.1 of the Ldap component, which no longer uses the same class, and now provides an LdapManager which can create new LDAP entries, or manipulate existing ones (update or delete).

I didn't add a documentation section regarding the legacy classes, but I figure that they should no longer be described as the main entry points for the Ldap component.

Commits
-------

066f5be Minor fixes
78ed43d Updated LDAP documentation for Symfony 3.1

Author: javiereguiluz

components/ldap.rst

@@ -25,8 +25,8 @@ and query against an LDAP server.
 
 The ``Ldap`` class uses an :class:`Symfony\\Component\\Ldap\\Adapter\\AdapterInterface`
 to communicate with an LDAP server. The :class:`adapter <Symfony\\Component\\Ldap\\Adapter\\ExtLdap\\Adapter>`
-for PHP's built-in LDAP extension, for example, can be configured
-using the following options:
+for PHP's built-in LDAP extension, for example, can be configured using the
+following options:
 
 ``host``
     IP or hostname of the LDAP server
@@ -38,31 +38,39 @@ using the following options:
     The version of the LDAP protocol to use
 
 ``encryption``
-    The encryption protocol : ``ssl``, ``tls`` or ``none`` (default)
+    The encryption protocol: ``ssl``, ``tls`` or ``none`` (default)
+
+``connection_string``
+    You may use this option instead of ``host`` and ``port`` to connect to the
+    LDAP server
+
+``optReferrals``
+    Specifies whether to automatically follow referrals returned by the LDAP server
 
 ``options``
-    LDAP server's options as defined in :class:`ConnectionOptions <Symfony\\Component\\Ldap\\Adapter\\ExtLdap\\ConnectionOptions>`
+    LDAP server's options as defined in
+    :class:`ConnectionOptions <Symfony\\Component\\Ldap\\Adapter\\ExtLdap\\ConnectionOptions>`
 
 For example, to connect to a start-TLS secured LDAP server::
 
-    use Symfony\Component\Ldap\Adapter\ExtLdap\Adapter;
     use Symfony\Component\Ldap\Ldap;
 
-    $adapter = new Adapter(array(
+    $ldap = Ldap::create('ext_ldap', array(
         'host' => 'my-server',
-        'port' => 389,
-        'encryption' => 'tls',
-        'options' => array(
-            'protocol_version' => 3,
-            'referrals' => false,
-        ),
+        'encryption' => 'ssl',
     ));
-    $ldap = new Ldap($adapter);
+
+Or you could directly specify a connection string::
+
+    use Symfony\Component\Ldap\Ldap;
+
+    $ldap = Ldap::create('ext_ldap', array('connection_string' => 'ldaps://my-server:636'));
 
 The :method:`Symfony\\Component\\Ldap\\Ldap::bind` method
 authenticates a previously configured connection using both the
 distinguished name (DN) and the password of a user::
 
+    use Symfony\Component\Ldap\Ldap;
     // ...
 
     $ldap->bind($dn, $password);
@@ -71,6 +79,7 @@ Once bound (or if you enabled anonymous authentication on your
 LDAP server), you may query the LDAP server using the
 :method:`Symfony\\Component\\Ldap\\Ldap::query` method::
 
+    use Symfony\Component\Ldap\Ldap;
     // ...
 
     $query = $ldap->query('dc=symfony,dc=com', '(&(objectclass=person)(ou=Maintainers))');
@@ -85,19 +94,21 @@ all entries in a single call and do something with the results'
 array, you may use the
 :method:`Symfony\\Component\\Ldap\\Adapter\\ExtLdap\\Collection::toArray` method::
 
+    use Symfony\Component\Ldap\Ldap;
     // ...
 
     $query = $ldap->query('dc=symfony,dc=com', '(&(objectclass=person)(ou=Maintainers))');
     $results = $query->execute()->toArray();
 
     // Do something with the results array
 
-Creating or updating entries
+Creating or Updating Entries
 ----------------------------
 
-Since version 3.1, The Ldap component provides means to create
-new LDAP entries, update or even delete existing ones::
+The Ldap component provides means to create new LDAP entries, update or even
+delete existing ones::
 
+    use Symfony\Component\Ldap\Ldap;
     use Symfony\Component\Ldap\Entry;
     // ...