docs/differences/python_35: Mark PEP 486 as not applicable.

This adds the "Not relevant" designation to PEP 486 since it has to do with
the Python Launcher for Windows and not the Python language itself.

Also fix a typo while we are touching this line.

Signed-off-by: David Lechner <david@pybricks.com>

docs/differences/python_35.rst

@@ -33,7 +33,7 @@ Below is a list of finalised/accepted PEPs for Python 3.5 grouped into their imp
    +--------------------------------------------------------+-------------------------------------------------+---------------+
    | `PEP 441 <https://www.python.org/dev/peps/pep-0441/>`_ | improved Python zip application support         |               |
    +--------------------------------------------------------+-------------------------------------------------+---------------+
-   | `PEP 486 <https://www.python.org/dev/peps/pep-0486/>`_ | make the Python Laucher aware of virtual        |               |
+   | `PEP 486 <https://www.python.org/dev/peps/pep-0486/>`_ | make the Python Launcher aware of virtual       | Not relevant  |
    |                                                        | environments                                    |               |
    +--------------------------------------------------------+-------------------------------------------------+---------------+
    | `PEP 484 <https://www.python.org/dev/peps/pep-0484/>`_ | type hints (advisory only)                      | In Progress   |