Add sphinx-rtd-theme extension

Author: Legrandin

Doc/conf.py

@@ -54,7 +54,8 @@ def have_aes_ni(self):
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = [ 'sphinx.ext.autodoc', 'sphinx.ext.napoleon',
-        'sphinx.ext.mathjax', 'sphinx_autodoc_typehints' ]
+               'sphinx.ext.mathjax', 'sphinx_autodoc_typehints',
+               'sphinx-rtd-theme' ]
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']