add documentation of how to recreate irods sha2 format

pymods/irods_utils/irods_utils.py

@@ -394,6 +394,8 @@ def confirmed_put( irods_sesh, file_pathname, new_obj_ipath, metadata_dict=None,
                      + " tmp ipath: "     + new_obj_ipath_tmp )
         return None
 
+    # Example here: https://github.com/irods/python-irodsclient/blob/main/irods/test/helpers.py#L251
+    # ... in function: def compute_sha256_digest(file_path):
     b64_digest256 = base64.b64encode(hash_digest256).decode()
     new_obj_hash_256 = "sha2:{}".format(b64_digest256)