Update README.md

Author: davetcc

README.md

@@ -85,6 +85,10 @@ Then in the loop method you need to call:
 
 TaskManagerIO library is not a full RTOS, rather it can be used on top of FreeRTOS via ESP32 or mbed RTOS. It is a complimentary technology that can assist with certain types of work-load. It has a major advantage, that the same code runs on many platforms as listed above. It is a core building block of [IoAbstraction](https://github.com/davetcc/IoAbstraction) and [tcMenu framework](https://github.com/davetcc/IoAbstraction)
 
+## Important notes around scheduling tasks and events
+
+TaskManaagerIO is a cooperative scheduler, and cooperative schedulers by their very nature have unfair semantics. In practice this means that you should not create repeating events or fixed rate schedules that have a 0 delay, if you do, no other tasks will run because the one with 0 delay will always win.  
+
 ## Multi-tasking - advanced usage
 
 TaskManager uses a lock free design, based on "compare and exchange" to acheive thread safety on larger boards, atomic operations on AVR, and interrupt locking back-up on other boards. Below, we discuss the multi-threaded features in more detail.