✨ Re-export Starlette's WebSocketException and add it to docs (#5629)

fastapi/__init__.py

@@ -8,6 +8,7 @@ from .applications import FastAPI as FastAPI
 from .background import BackgroundTasks as BackgroundTasks
 from .datastructures import UploadFile as UploadFile
 from .exceptions import HTTPException as HTTPException
+from .exceptions import WebSocketException as WebSocketException
 from .param_functions import Body as Body
 from .param_functions import Cookie as Cookie
 from .param_functions import Depends as Depends

fastapi/exceptions.py

@@ -3,6 +3,7 @@ from typing import Any, Dict, Optional, Sequence, Type
 from pydantic import BaseModel, ValidationError, create_model
 from pydantic.error_wrappers import ErrorList
 from starlette.exceptions import HTTPException as StarletteHTTPException
+from starlette.exceptions import WebSocketException as WebSocketException  # noqa: F401
 
 
 class HTTPException(StarletteHTTPException):