fix

conf.py

@@ -38,7 +38,7 @@
 # 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_rtd_theme", ]
+extensions = [ "sphinx-rtd-theme", ]
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']