Add warning about macOS 12 to stable (#2296)

Author: sciencewhiz

source/docs/zero-to-robot/step-2/wpilib-setup.rst

@@ -11,6 +11,8 @@ Supported Operating Systems and Architectures:
  * Ubuntu 22.04, 64 bit. Other Linux distributions with glibc >= 2.34 may work, but are unsupported
  * macOS 11 or higher, both Intel and Arm.
 
+.. warning:: For 2024, macOS 12 or higher will be required for C++
+
 .. warning:: The following OSes are no longer supported: macOS 10.15, Ubuntu 18.04 & 20.04, Windows 7, Windows 8.1, and any 32-bit Windows.
 
 WPILib is designed to install to different folders for different years, so that it is not necessary to uninstall a previous version before installing this year's WPILib.