Add README_cmake.md to distrib
Add README_cmake.md to distrib


Former-commit-id: 2eba1633dc40a4afdb41de317964c90f4b1b36a6
Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide