docs: more comments

Author: georgeh0

docs/docs/core/data_types.mdx

@@ -120,7 +120,7 @@ For example:
 ```python
 from dataclasses import dataclass
 from typing import NamedTuple
-from pydantic import BaseModel
+from pydantic import BaseModel   # requires `pydantic` package to be installed
 import datetime
 
 # Using dataclass