Update Doc/library/threading.rst

Co-authored-by: Peter Bierma <zintensitydev@gmail.com>

Author: donbarbos

Doc/library/threading.rst

@@ -92,6 +92,9 @@ creating and starting threads using :class:`~threading.Thread`::
        # Using `args` to pass positional arguments and `kwargs` for keyword arguments
        t = threading.Thread(target=crawl, args=(link,), kwargs={"delay": 2})
        threads.append(t)
+
+    # Start each thread
+    for t in threads:
        t.start()
 
    # Wait for all threads to finish