Update components/yaml.rst

Co-authored-by: Christian Flothmann <[email protected]>

Author: alamirault

components/yaml.rst

@@ -418,7 +418,7 @@ you can dump them as ``~`` with the ``DUMP_NULL_AS_TILDE`` flag::
     $dumped = Yaml::dump(['foo' => null], 2, 4, Yaml::DUMP_NULL_AS_TILDE);
     // foo: ~
 
-Dumping Numeric Keys as string
+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