bug symfony#4522 Add missing brackets to PropertyAccessor examples (loonytoons)

This PR was merged into the 2.5 branch.

Discussion
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Add missing brackets to PropertyAccessor examples

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.5+
| Fixed tickets | none

Commits
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d6b4795 Add missing brackets to PropertyAccessor examples

Author: wouterj

components/property_access/introduction.rst

@@ -327,7 +327,7 @@ instead::
 
     $person = new Person();
 
-    if ($accessor->isReadable($person, 'firstName') {
+    if ($accessor->isReadable($person, 'firstName')) {
         // ...
     }
 
@@ -338,7 +338,7 @@ method to find out whether a property path can be updated::
 
     $person = new Person();
 
-    if ($accessor->isWritable($person, 'firstName') {
+    if ($accessor->isWritable($person, 'firstName')) {
         // ...
     }