Change Mac OS X to OS X

Apple has renamed Mac OS X to OS X.

README.md

@@ -25,7 +25,7 @@ Please follow the instructions for your platform:
 
 - [UNIX](https://github.com/miguelfreitas/twister-core/blob/master/doc/build-unix.md)
 - [Debian/Ubuntu](https://github.com/miguelfreitas/twister-core/blob/master/doc/building-on-ubuntu-debian.md)
-- [Mac OS X](https://github.com/miguelfreitas/twister-core/blob/master/doc/build-osx.md)
+- [OS X](https://github.com/miguelfreitas/twister-core/blob/master/doc/build-osx.md)
 - [Windows (untested)](https://github.com/miguelfreitas/twister-core/wiki/Compiling-for-Windows)
 
 > According to our tests, at least 1GB of RAM is needed to compile Twister.

doc/build-osx.md

@@ -1,4 +1,4 @@
-Mac OS X Build Instructions and Notes
+OS X Build Instructions and Notes
 ====================================
 This guide will show you how to build twisterd for OS X.