chore: Improve APIConnectionTimeoutError message.

PiperOrigin-RevId: 916821324

Author: wanlin31

google/genai/_interactions/_exceptions.py

@@ -88,8 +88,7 @@ def __init__(self, *, message: str = "Connection error.", request: httpx.Request
 
 class APITimeoutError(APIConnectionError):
     def __init__(self, request: httpx.Request) -> None:
-        super().__init__(message="Request timed out.", request=request)
-
+        super().__init__(message="Request timed out. This is a client-side timeout. You can increase the timeout by setting the `timeout` argument on your request or in the client http options.", request=request)
 
 class BadRequestError(APIStatusError):
     status_code: Literal[400] = 400  # pyright: ignore[reportIncompatibleVariableOverride]