Improve text

Author: alamirault

components/yaml.rst

@@ -421,8 +421,8 @@ you can dump them as ``~`` with the ``DUMP_NULL_AS_TILDE`` flag::
 Dumping Numeric Keys as Strings
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Sometime YAML keys must be always string. This component don't convert keys to string by default but you can
-make it convert numeric keys as string by using the ``DUMP_NUMERIC_KEY_AS_STRING`` flag::
+By default, digit-only array keys are dumped as integers. You can use the
+``DUMP_NUMERIC_KEY_AS_STRING`` flag if you want to dump string-only keys::
 
     $dumped = Yaml::dump([200 => 'foo']);
     // 200: foo