docs(readme): fix wrong formatting

Author: deveaud-m

README.rst

@@ -91,8 +91,7 @@ Develop
    `docstrings <https://realpython.com/documenting-python-code/>`__ to
    document functions and classes
 
--  Extend the testsuite `poetry run pytest`_ with the
-   new functions/classes
+-  Extend the testsuite **poetry run pytest** with the new functions/classes
 
 -  The **documentation website** can automatically be generated by the `Sphinx autodoc
    extension <http://www.sphinx-doc.org/en/master/usage/extensions/autodoc.html>`_