📝 Update `docs/en/docs/tutorial/body.md` with Python 3.10 union type example (#11415)

Co-authored-by: svlandeg <[email protected]>
Co-authored-by: Sebastián Ramírez <[email protected]>

docs/en/docs/tutorial/body.md

@@ -237,7 +237,9 @@ The function parameters will be recognized as follows:
 
 FastAPI will know that the value of `q` is not required because of the default value `= None`.
 
-The `Union` in `Union[str, None]` is not used by FastAPI, but will allow your editor to give you better support and detect errors.
+The `str | None` (Python 3.10+) or `Union` in `Union[str, None]` (Python 3.8+) is not used by FastAPI to determine that the value is not required, it will know it's not required because it has a default value of `= None`.
+
+But adding the type annotations will allow your editor to give you better support and detect errors.
 
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