Merge branch '5.1' into 5.2

* 5.1:
  [Validator] Use single quotes for string
  [Validator] Use double quotes instead of single
  [Workflow] Added initialization docs

Author: OskarStark

components/workflow.rst

@@ -94,6 +94,20 @@ you can retrieve a workflow from it and use it as follows::
     $workflow->can($blogPost, 'publish'); // True
     $workflow->getEnabledTransitions($blogPost); // $blogPost can perform transition "publish" or "reject"
 
+Initialization
+--------------
+
+If the property of your object is ``null`` and you want to set it with the
+``initial_marking`` from the configuration, you can call the ``getMarking()``
+method to initialize the object property::
+
+    // ...
+    $blogPost = new BlogPost();
+    $workflow = $registry->get($blogPost);
+
+    // initiate workflow
+    $workflow->getMarking($blogPost);
+
 Learn more
 ----------
 

reference/constraints/IsFalse.rst

@@ -115,7 +115,7 @@ method returns **false**:
             public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addGetterConstraint('stateInvalid', new Assert\IsFalse([
-                    'message' => 'You've entered an invalid state.',
+                    'message' => "You've entered an invalid state.",
                 ]));
             }
         }

reference/constraints/Sequentially.rst

@@ -120,7 +120,7 @@ You can validate each of these constraints sequentially to solve these issues:
             {
                 $metadata->addPropertyConstraint('address', new Assert\Sequentially([
                     new Assert\NotNull(),
-                    new Assert\Type("string"),
+                    new Assert\Type('string'),
                     new Assert\Length(['min' => 10]),
                     new Assert\Regex(self::ADDRESS_REGEX),
                     new AcmeAssert\Geolocalizable(),