update docstring to take Path or str

Author: cadenmyers13

src/diffpy/cmi/packsmanager.py

@@ -146,7 +146,7 @@ def copy_examples(
         ----------
         examples_to_copy : list of str
             User-specified pack(s), example(s), or "all" to copy all.
-        target_dir : pathlib.Path, optional
+        target_dir : pathlib.Path or str, optional
             Target directory to copy examples into. Defaults to current
             working directory.
         force : bool, optional