DOC: clarify extension document

Co-authored-by: Chris Havlin <chris.havlin@gmail.com>

doc/source/developing/extensions.rst

@@ -40,7 +40,10 @@ Frontend as an extension
 
 Starting with version 4.2 of yt, any externally installed package that exports
 :class:`~yt.data_objects.static_output.Dataset` subclass as an entrypoint in
-``yt.frontends`` namespace in ``setup.py``:
+``yt.frontends`` namespace in ``setup.py`` or ``pyproject.toml`` will be 
+automatically loaded and immediately available in :func:`~yt.loaders.load`.
+
+To add an entrypoint in an external project's ``setup.py``:
 
 .. code-block:: python
 
@@ -62,8 +65,6 @@ or ``pyproject.toml``:
    myFrontend = "my_frontend.api:MyFrontendDataset"
    myOtherFrontend = "my_frontend.api:MyOtherFrontendDataset"
 
-will be automatically loaded and immediately available in
-:func:`~yt.loaders.load`.
 
 Extension Template
 ------------------