Update job_executor/adapter/fs/private_keys_directory.py

Co-authored-by: Daniel Elisenberg <33904479+DanielElisenberg@users.noreply.github.com>

Author: pawbu

job_executor/adapter/fs/private_keys_directory.py

@@ -14,6 +14,11 @@ def create(self) -> bool:
         return False
 
     def save_private_key(self, microdata_private_key_pem: bytes) -> None:
+        """
+        Write the new private key file so only the owner of the 
+        file (this application) has read and write permissions.
+        Fails and raises an exception if the file exists. 
+        """
         fd = os.open(
             self._get_private_key_location(),
             os.O_CREAT | os.O_WRONLY | os.O_EXCL,