minor symfony#8554 [Yaml] remove deprecated feature description (xabbuh)

This PR was merged into the 3.3 branch.

Discussion
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[Yaml] remove deprecated feature description

Commits
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cd2c809 remove deprecated feature description

Author: weaverryan

components/yaml.rst

@@ -104,12 +104,6 @@ string and converts it to a PHP array:
 
     $value = Yaml::parse(file_get_contents('/path/to/file.yml'));
 
-.. caution::
-
-    Because it is currently possible to pass a filename to this method, you
-    must validate the input first. Passing a filename is deprecated in
-    Symfony 2.2, and was removed in Symfony 3.0.
-
 If an error occurs during parsing, the parser throws a
 :class:`Symfony\\Component\\Yaml\\Exception\\ParseException` exception
 indicating the error type and the line in the original YAML string where the