Fix setting sys.path when building docs

docs/conf.py

@@ -11,13 +11,12 @@
 # All configuration values have a default; values that are commented out
 # serve to show the default.
 
-import sys, os
+import sys
 import configparser
+from pathlib import Path
 
-# If extensions (or modules to document with autodoc) are in another directory,
-# 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('..'))
+# Allow importing nptdms from the parent directory for building API docs
+sys.path.insert(0, str(Path(__file__).parent.parent))
 
 # -- General configuration -----------------------------------------------------