Revert "Update README to use optional dependency over requirements.txt" In 4ab4de3bb (Update README to use optional dependency over requirements.txt, 2022-09-06), docs/README.rst was changed to suggest installing the requirements for the documentation build using 'pip install .[doc] -U' instead of using docs/requirements.txt. This works for a first build but since it is not an editable install, any changes to the docstrings are not reflected in the generated API section in subsequent builds, since Sphinx's autodoc extensions looks at installed modules only. Revert that commit, going back to suggesting 'pip install -U -r docs/requirements.txt'. The requirements file itself consists of '-e .[doc]' since 95de1fe40 (Move documentation requirements to setup.cfg, 2022-09-06) (the parent of the commit we are reverting), so this does not change the list of installed packages. This reverts commit 4ab4de3bbf08805262e4b67957faf2e2c588e382.