minor #5474 typo in components/translation/instruction.rst (beesofts)

This PR was submitted for the 2.7 branch but it was merged into the 2.3 branch instead (closes #5474).

Discussion
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typo in components/translation/instruction.rst

$translator->setFallbackLocale() should be $translator->setFallbackLocales()

Commits
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fda8ff5 typo in components/translation/instruction.rst

components/translation/introduction.rst

@@ -170,10 +170,10 @@ example, assume you're trying to translate into the ``fr_FR`` locale:
    fallback locales set explicitly on the translator.
 
 For (3), the fallback locales can be set by calling
-:method:`Symfony\\Component\\Translation\\Translator::setFallbackLocale`::
+:method:`Symfony\\Component\\Translation\\Translator::setFallbackLocales`::
 
     // ...
-    $translator->setFallbackLocale(array('en'));
+    $translator->setFallbackLocales(array('en'));
 
 .. _using-message-domains: