Subject: PEP role: Include trailing / in URL to avoid 301 redirect

Feature or Bugfix

• Feature

Purpose

• Link :pep:8 to https://peps.python.org/pep-0008/ instead of https://peps.python.org/pep-0008

Detail

• Without the trailing /, there's an HTTP 301 redirect to add the slash, which adds a small but unnecessary delay

Without trailing /, the 301 may take between 20ms and 335ms (caching off)

With the trailing /, that request is skipped

• Also update docs and docstrings to use the new form.

Relates

• environment: Update default value for pep_base_url #10267