Add a warning to schedule docs (#70)

Author: spacey-sooty

Diff for: commands2/commandscheduler.py

@@ -177,6 +177,9 @@ def schedule(self, *commands: Command) -> None:
         using those requirements have been scheduled as interruptible. If this is the case, they will
         be interrupted and the command will be scheduled.
 
+        WARNING: using this function directly can often lead to unexpected behavior and should be
+        avoided. Instead Triggers should be used to schedule Commands.
+
         :param commands: the commands to schedule.
         """
         for command in commands: