Updated CMake Build Options (markdown)

CMake-Build-Options.md

@@ -1,6 +1,6 @@
 raylib is configurable and can be built in a variety of ways. Following is a listing of available CMake options and values, extracted from [`src/CMakeOptions.txt`](https://github.com/raysan5/raylib/blob/204872de0947c3f0c3b7bc1319c2d7e1b9568498/CMakeOptions.txt) and [`src/config.h`](https://github.com/raysan5/raylib/blob/204872de0947c3f0c3b7bc1319c2d7e1b9568498/src/config.h)
 
-You must define `-DCUSTOMIZE_BUILD=ON` in order for many of these options to apply.
+You must set `CUSTOMIZE_BUILD` to ON in order for many of these options to apply.
 
 > **TIP**:  You can use the curses UI provided by `ccmake(1)` for interactively configuring raylib.