Add a note about Arduino.org

Author: sudar

README.md

@@ -259,6 +259,7 @@ If you are looking for ideas to work on, then check out the following TODO items
 - Since it doesn't do any pre processing like Arduino IDE, you have to declare all methods before you use them ([issue #59](https://github.com/sudar/Arduino-Makefile/issues/59))
 - More than one .ino or .pde file is not supported yet ([issue #49](https://github.com/sudar/Arduino-Makefile/issues/49))
 - When you compile for the first time, it builds all libs inside Arduino directory even if it is not needed. But while linking only the relevant files are linked. ([issue #29](https://github.com/sudar/Arduino-Makefile/issues/29)). Even Arduino IDE does the same thing though.
+- This makefile doesn't support boards or IDE from Arduino.org.
 
 If you find an issue or have an idea for a feature then log them in the [issue tracker](https://github.com/sudar/Arduino-Makefile/issues/)