[CMake] Documenting boolean evaluation

[Pau Garcia i Quiles]

Hello,

Back in June Dr. Ken Martin implemented parentheses in conditionals (
http://thread.gmane.org/gmane.comp.programming.tools.cmake.user/14569
) but I have not found that feature documented anywhere in 2.6.2. I
would like to suggest this is documented in the IF command for 2.6.3.

Thanks.

-- 
Pau Garcia i Quiles
http://www.elpauer.org
(Due to my workload, I may need 10 days to answer)