Document the advantages of this plugin over using Flake8 and Pytest separately.

[simon-liebehenschel]

I run at my projects Continuous Integration separately Flake8 and Pytest.

Honesty, I have no clue what is the purpose of this plugin if anyone can run Flake8 at his CI and then Pytest.

[jaraco]

Have a look at jaraco/skeleton#48 (comment) for reasons why the plugin is useful to me over a simple executable.