Update Doc/library/asyncio-eventloop.rst

Co-authored-by: Thomas Grainger <[email protected]>

Author: kumaraditya303

Doc/library/asyncio-eventloop.rst

@@ -246,7 +246,8 @@ Scheduling callbacks
    another thread, this function *must* be used, since :meth:`call_soon` is not
    thread-safe.
 
-   This function is safe to be called from a re-entrant context or signal handler.
+   This function is safe to be called from a re-entrant context or signal handler,
+   however, it is not safe or fruitful to use the returned handle in such contexts.
 
    Raises :exc:`RuntimeError` if called on a loop that's been closed.
    This can happen on a secondary thread when the main application is