Better docstring for _signal_handler

certbot/error_handler.py

@@ -112,7 +112,8 @@ class ErrorHandler(object):
         self.prev_handlers.clear()
 
     def _signal_handler(self, signum, unused_frame):
-        """Stores the recieved signal.
+        """Stores the recieved signal. If we are executing the code block in
+        the body of the context manager, stop by raising signal exit.
 
         :param int signum: number of current signal