Correct minor grammar mistake (GH-15404)

Author: andresdelfino

Doc/library/json.rst

@@ -129,7 +129,7 @@ See :ref:`json-commandline` for detailed documentation.
  inputs and outputs were typically scrambled unless
  :class:`collections.OrderedDict` was specifically requested. Starting
  with Python 3.7, the regular :class:`dict` became order preserving, so
- it is no longer necessary specify :class:`collections.OrderedDict` for
+ it is no longer necessary to specify :class:`collections.OrderedDict` for
  JSON generation and parsing.