$ python3 -m venv ./venv
$ source ./venv/bin/activate
$ pip install sphinx
$ git clone git@github.com:arekfu/sphinx-issue-pep.git && cd sphinx-issue-pep
$ sphinx-build -b linkcheck . _build
Running Sphinx v4.4.0
building [mo]: targets for 0 po files that are out of date
building [linkcheck]: targets for 1 source files that are out of date
updating environment: [new config] 1 added, 0 changed, 0 removed
reading sources... [100%] index
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [100%] index

(           index: line    4) redirect  https://www.python.org/dev/peps/pep-0008 - permanently to https://peps.python.org/pep-0008/
build succeeded.

Look for any errors in the above output or in _build/output.txt