minor symfony#4438 Fix typo: Objected => Object (ifdattic)

This PR was merged into the 2.3 branch.

Discussion
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Fix typo: Objected => Object

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3
| Fixed tickets |

Commits
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4d98ebf Fix typo: Objected => Object

Author: wouterj

components/event_dispatcher/introduction.rst

@@ -12,7 +12,7 @@ The EventDispatcher Component
 Introduction
 ------------
 
-Objected Oriented code has gone a long way to ensuring code extensibility. By
+Object Oriented code has gone a long way to ensuring code extensibility. By
 creating classes that have well defined responsibilities, your code becomes
 more flexible and a developer can extend them with subclasses to modify their
 behaviors. But if they want to share the changes with other developers who have