add includes field

Author: feilipu

library.properties

@@ -1,9 +1,10 @@
 name=FreeRTOS
-version=8.2.3-17
+version=8.2.3-18
 author=Richard Berry <[email protected]>
 maintainer=Phillip Stevens <[email protected]>
 sentence=Real Time Operating System implemented for AVR (Uno, Leonardo, Mega).
 paragraph=The primary design goals are: Easy to use, Small footprint, Robust. Uses Watchdog Timer for 15ms resolution. Slow blink = stack overflow. Fast blink = heap malloc() failure.
 category=Timing
 url=https://github.com/feilipu/Arduino_FreeRTOS_Library
 architectures=avr
+includes=Arduino_FreeRTOS.h