fix docs config

Author: Žiga Stupan

docs/source/conf.py

@@ -12,9 +12,10 @@
 # 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.
 #
-import os
 import sys
-sys.path.insert(0, os.path.abspath('../../'))
+from pathlib import Path
+
+sys.path.insert(0, str(Path('..', '..', 'src').resolve()))
 
 # -- Project information -----------------------------------------------------