OSX: Fix typo

reference/compiling_for_osx.rst

@@ -65,7 +65,7 @@ Now you can compile with SCons like you normally would:
 
     user@host:~/godot$ scons platform=osx
 
-If you have an OSXCross SDK version different from the one expected by the SCons buildsystem, you can specify a custom one with the ``osxcross`` argument:
+If you have an OSXCross SDK version different from the one expected by the SCons buildsystem, you can specify a custom one with the ``osxcross_sdk`` argument:
 
 ::