Update CMake docs: ENABLE_UNITY_BUILD defaults to ON (#2038)

Author: specious

Docs/CMake_Parameters.md

@@ -50,7 +50,7 @@ Windows example:
 For more information, see the CMake documentation for your platform.
 
 ### ENABLE_UNITY_BUILD
-(Defaults to OFF) If enabled, most SDK libraries will be built as a single, generated .cpp file.  This can significantly reduce static library size as well as speed up compilation time.
+(Defaults to ON) If enabled, most SDK libraries will be built as a single, generated .cpp file.  This can significantly reduce static library size as well as speed up compilation time.
 
 ### MINIMIZE_SIZE
 (Defaults to OFF) A superset of ENABLE_UNITY_BUILD, if enabled this option turns on ENABLE_UNITY_BUILD as well as some additional binary size reduction settings.  This is a work-in-progress and may change in the future (symbol stripping in particular).