fix docs

docs/conf.py

@@ -13,6 +13,7 @@ with open('../pyotrs/version.py') as f:
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 sys.path.insert(0, os.path.abspath('../'))
+sys.path.insert(0, os.path.abspath(os.path.join('..', '..'))
 
 # -- General configuration ------------------------------------------------