Infra: Link breadcrumbs back to homepage not /pep-0000/

[hugovk]

Right now:

1. Go to https://peps.python.org/
2. Click on a PEP: https://peps.python.org/pep-0008/
3. In the breadcrumbs at the top: "Python » PEP Index » PEP 8", click "PEP Index"

Expected result:

• Taken back to https://peps.python.org/

Actual result:

• Taken to https://peps.python.org/pep-0000/

That /pep-0000/ is confusing, let's go back to the usual / instead.

[willingc]

Thanks @hugovk.