Update code examples in `docs/index.md` to follow latest Python syntax

docs/en/docs/index.md

@@ -161,8 +161,6 @@ $ pip install "fastapi[standard]"
 Create a file `main.py` with:
 
 ```Python
-from typing import Union
-
 from fastapi import FastAPI
 
 app = FastAPI()
@@ -174,7 +172,7 @@ def read_root():
 
 
 @app.get("/items/{item_id}")
-def read_item(item_id: int, q: Union[str, None] = None):
+def read_item(item_id: int, q: str | None = None):
     return {"item_id": item_id, "q": q}
 ```
 
@@ -183,9 +181,7 @@ def read_item(item_id: int, q: Union[str, None] = None):
 
 If your code uses `async` / `await`, use `async def`:
 
-```Python hl_lines="9  14"
+```Python hl_lines="7  12"
-from typing import Union
-
 from fastapi import FastAPI
 
 app = FastAPI()
@@ -197,7 +193,7 @@ async def read_root():
 
 
 @app.get("/items/{item_id}")
-async def read_item(item_id: int, q: Union[str, None] = None):
+async def read_item(item_id: int, q: str | None = None):
     return {"item_id": item_id, "q": q}
 ```
 
@@ -288,9 +284,7 @@ Now modify the file `main.py` to receive a body from a `PUT` request.
 
 Declare the body using standard Python types, thanks to Pydantic.
 
-```Python hl_lines="4  9-12  25-27"
+```Python hl_lines="2  7-10 23-25"
-from typing import Union
-
 from fastapi import FastAPI
 from pydantic import BaseModel
 
@@ -300,7 +294,7 @@ app = FastAPI()
 class Item(BaseModel):
     name: str
     price: float
-    is_offer: Union[bool, None] = None
+    is_offer: bool | None = None
 
 
 @app.get("/")
@@ -309,7 +303,7 @@ def read_root():
 
 
 @app.get("/items/{item_id}")
-def read_item(item_id: int, q: Union[str, None] = None):
+def read_item(item_id: int, q: str | None = None):
     return {"item_id": item_id, "q": q}