Update documentation

Author: AA-Turner

doc/internals/contributing.rst

@@ -201,7 +201,7 @@ You can also test by installing dependencies in your local environment:
 
   .. code-block:: shell
 
-     pip install .[test]
+     pip install . --group test
 
 To run JavaScript tests, use :program:`npm`:
 

doc/usage/installation.rst

@@ -57,6 +57,8 @@ Run the following command::
    place the dependencies in the `pyproject.toml file`__::
 
       $ pip install .[docs]
+      # or
+      $ pip install . --group docs
 
    __ https://pip.pypa.io/en/stable/reference/requirements-file-format/
    __ https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#dependencies-optional-dependencies