Corrige a configuração do build do Read The Docs

docs/conf.py

@@ -45,6 +45,8 @@ language = 'pt_BR'
 # This pattern also affects html_static_path and html_extra_path.
 exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
 
+# The master toctree document.
+master_doc = 'index'
 
 # -- Options for HTML output ----------------------------------------------