docs: Update function docstring

Author: caffeine-addictt

src/thread/thread.py

@@ -260,10 +260,11 @@ def kill(self, yielding: bool = False, timeout: float = 5) -> bool:
 
     Returns
     -------
-    :returns bool: False if the it exceeded the timeout
+    :returns bool: False if the it exceeded the timeout without being killed
 
     Raises
     ------
+    ValueError: If the thread ident does not exist
     ThreadNotInitializedError: If the thread is not initialized
     ThreadNotRunningError: If the thread is not running
     """