docs: update docs domain to docs.saltproject.io

Author: dafyddj

docs/README.rst

@@ -28,15 +28,15 @@ General notes
 -------------
 
 See the full `SaltStack Formulas installation and usage instructions
-<https://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html>`_.
+<https://docs.saltproject.io/en/latest/topics/development/conventions/formulas.html>`_.
 
 If you are interested in writing or contributing to formulas, please pay attention to the `Writing Formula Section
-<https://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html#writing-formulas>`_.
+<https://docs.saltproject.io/en/latest/topics/development/conventions/formulas.html#writing-formulas>`_.
 
 If you want to use this formula, please pay attention to the ``FORMULA`` file and/or ``git tag``,
 which contains the currently released version. This formula is versioned according to `Semantic Versioning <http://semver.org/>`_.
 
-See `Formula Versioning Section <https://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html#versioning>`_ for more details.
+See `Formula Versioning Section <https://docs.saltproject.io/en/latest/topics/development/conventions/formulas.html#versioning>`_ for more details.
 
 If you need (non-default) configuration, please refer to: