added the TOML Spec link to the documentation

docs/basics.rst

@@ -127,6 +127,7 @@ Example Pipfile.lock
 - Do not keep ``Pipfile.lock`` in version control if multiple versions of Python are being targeted.
 - Specify your target Python version in your `Pipfile`'s ``[requires]`` section. Ideally, you should only have one target Python version, as this is a deployment tool.
 - ``pipenv install`` is fully compatible with ``pip install`` syntax, for which the full documentation can be found `here <https://pip.pypa.io/en/stable/user_guide/#installing-packages>`_.
+- Note that the ``Pipfile`` uses the `TOML Spec <https://github.com/toml-lang/toml#user-content-spec>`_.