Fix broken Kedro hooks link

[simonw]

The Kedro link on https://pluggy.readthedocs.io/en/stable/#more-real-world-examples

To see how pluggy is used in the real world, have a look at these projects documentation and source code:

• pytest
• tox
• devpi
• kedro

Links to https://docs.kedro.org/en/latest/kedro.framework.hooks.specs.html which returns a 404 error

I think https://docs.kedro.org/en/latest/hooks/introduction.html is a better page to link to here.

[simonw]

The test failure here was from codecov which shouldn't be relevant to this change since it is documentation only.

[simonw]

I ran the Sphinx build locally to confirm that this produces the correct URL, and it does.

cd pluggy/docs
pip install -r requirements.txt
pip install -e ..
sphinx-build . out
open out/index.html