bug #4905 Update routing.rst (IlhamiD)

This PR was submitted for the 2.6 branch but it was merged into the 2.3 branch instead (closes #4905).

Discussion
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Update routing.rst

corrected a few typos.

Commits
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cf48e1a Update routing.rst

Author: wouterj

book/routing.rst

@@ -945,8 +945,8 @@ routing system can be:
             /**
              * @Route(
              *     "/articles/{_locale}/{year}/{title}.{_format}",
-             *     defaults: {"_format": "html"},
-             *     requirements: {
+             *     defaults={"_format": "html"},
+             *     requirements={
              *         "_locale": "en|fr",
              *         "_format": "html|rss",
              *         "year": "\d+"