docs: fix typos (#433)

Found via `codespell -H -S sting`

Author: kianmeng

src/vcspull/cli/sync.py

@@ -1,4 +1,4 @@
-"""Synchronization functionailty for vcspull."""
+"""Synchronization functionality for vcspull."""
 import argparse
 import logging
 import pathlib

src/vcspull/config.py

@@ -1,4 +1,4 @@
-"""Configuration functionailty for vcspull."""
+"""Configuration functionality for vcspull."""
 import fnmatch
 import logging
 import os